add missing input file

Batch adjacent same-texture sprite draws in end_frame.
Replaces per-sprite DrawGPUPrimitives with texture runs so shared atlases issue one GPU draw.

Makefile

@@ -1,15 +1,19 @@
-.PHONY: shaders-vulkan shaders-d3d12 shaders-metal shaders-all bake toad check test help
+.PHONY: shaders-vulkan shaders-d3d12 shaders-metal shaders-all bake toad hello_sprite crowd camera_sandbox clips check test help
 
 help:
 	@echo "Targets:"
-	@echo "  bake            Bake all characters under content/characters/"
+	@echo "  bake             Bake all characters under content/characters/"
-	@echo "  shaders-vulkan  Compile SPIR-V into shaders/vulkan/"
+	@echo "  shaders-vulkan   Compile SPIR-V into shaders/vulkan/"
-	@echo "  shaders-d3d12   Compile DXIL into shaders/d3d12/ (needs shadercross)"
+	@echo "  shaders-d3d12    Compile DXIL into shaders/d3d12/ (needs shadercross)"
-	@echo "  shaders-metal   Compile MSL into shaders/metal/ (needs shadercross)"
+	@echo "  shaders-metal    Compile MSL into shaders/metal/ (needs shadercross)"
-	@echo "  shaders-all     Build all shader backends"
+	@echo "  shaders-all      Build all shader backends"
-	@echo "  test            Run engine unit tests"
+	@echo "  test             Run engine unit tests"
-	@echo "  check           Typecheck examples/toad"
+	@echo "  check            Typecheck all examples"
-	@echo "  toad            Run the toad example"
+	@echo "  toad             Run the toad example (full demo)"
+	@echo "  hello_sprite     Minimal load + draw"
+	@echo "  crowd            Many sprites, one Character_Data"
+	@echo "  camera_sandbox   Pan camera / Space toggles follow"
+	@echo "  clips            Keys 1/2 switch idle/walk"
 
 bake:
 	./scripts/bake_all.sh
@@ -30,6 +34,22 @@ test:
 
 check:
 	odin check examples/toad -collection:pkg=.
+	odin check examples/hello_sprite -collection:pkg=.
+	odin check examples/crowd -collection:pkg=.
+	odin check examples/camera_sandbox -collection:pkg=.
+	odin check examples/clips -collection:pkg=.
 
 toad:
 	odin run examples/toad -collection:pkg=.
+
+hello_sprite:
+	odin run examples/hello_sprite -collection:pkg=.
+
+crowd:
+	odin run examples/crowd -collection:pkg=.
+
+camera_sandbox:
+	odin run examples/camera_sandbox -collection:pkg=.
+
+clips:
+	odin run examples/clips -collection:pkg=.

assetbake/main.odin

@@ -56,10 +56,12 @@ Char_Def :: struct {
 
 // Packed atlas pixels + per-frame rects (indexed like the combined frames list)
 Atlas :: struct {
-	pixels: []u8,
+	pixels:        []u8,
-	width:  int,
+	width:         int,
-	height: int,
+	height:        int,
-	rects:  [][4]int, // [x, y, w, h] per frame; sizes may differ across clips
+	rects:         [][4]int,
+	source_sizes:  [][2]int,
+	trim_offsets:  [][2]int,
 }
 
 // Where one clip's frames sit inside the packed atlas frame list
@@ -95,6 +97,8 @@ bake_character :: proc(in_dir, out_dir: string) {
 	atlas := pack_atlas(frames)
 	defer delete(atlas.pixels)
 	defer delete(atlas.rects)
+	defer delete(atlas.source_sizes)
+	defer delete(atlas.trim_offsets)
 
 	ensure_dir(out_dir)
 
@@ -283,22 +287,56 @@ destroy_frames :: proc(frames: []^image.Image) {
 	delete(frames)
 }
 
-// pack_atlas packs variable-size frames with stb_rect_pack and blits them into one sheet.
+opaque_bounds :: proc(img: ^image.Image, alpha_min: u8 = 1) -> (x, y, w, h: int) {
-// Caller owns atlas.pixels and atlas.rects.
+	iw, ih := int(img.width), int(img.height)
+	pixels := bytes.buffer_to_bytes(&img.pixels)
+
+	min_x, min_y := iw, ih
+	max_x, max_y := -1, -1
+
+	for py in 0 ..< ih {
+		for px in 0 ..< iw {
+			i := (py * iw + px) * 4
+			a := pixels[i + 3]
+			if a >= alpha_min {
+				if px < min_x do min_x = px
+				if py < min_y do min_y = py
+				if px > max_x do max_x = px
+				if py > max_y do max_y = py
+			}
+		}
+	}
+
+	if max_x < min_x {
+		return 0, 0, 1, 1
+	}
+	return min_x, min_y, max_x - min_x + 1, max_y - min_y + 1
+}
+
 pack_atlas :: proc(frames: []^image.Image) -> Atlas {
-	PADDING :: 1 // 1px gap to reduce bleeding if filtered later
+	PADDING :: 1
 
 	pack_rects := make([]stbrp.Rect, len(frames))
 	defer delete(pack_rects)
 
+	trims := make([][4]int, len(frames))
+	defer delete(trims)
+	source_sizes := make([][2]int, len(frames))
+	trim_offsets := make([][2]int, len(frames))
+
 	total_area := 0
 	max_w := 0
 	max_h := 0
 	for frame, i in frames {
-		w := frame.width + PADDING
+		tx, ty, tw, th := opaque_bounds(frame)
-		h := frame.height + PADDING
+		trims[i] = {tx, ty, tw, th}
+		source_sizes[i] = {int(frame.width), int(frame.height)}
+		trim_offsets[i] = {tx, ty}
+
+		w := tw + PADDING
+		h := th + PADDING
 		pack_rects[i] = stbrp.Rect {
-			id = c.int(i), // pack_rects may reorder; id maps back to frame index
+			id = c.int(i),
 			w  = stbrp.Coord(w),
 			h  = stbrp.Coord(h),
 		}
@@ -307,7 +345,6 @@ pack_atlas :: proc(frames: []^image.Image) -> Atlas {
 		max_h = max(max_h, h)
 	}
 
-	// Grow a square-ish atlas until everything fits
 	side := max(max_w, max_h, int(math.ceil(math.sqrt(f64(total_area)))))
 	atlas_w, atlas_h := 0, 0
 	packed := false
@@ -326,10 +363,9 @@ pack_atlas :: proc(frames: []^image.Image) -> Atlas {
 		os.exit(1)
 	}
 
-	pixels := make([]u8, atlas_w * atlas_h * 4) // transparent
+	pixels := make([]u8, atlas_w * atlas_h * 4)
 	rects := make([][4]int, len(frames))
 
-	// Blit using each rect's id (array order may have changed during packing)
 	for pr in pack_rects {
 		if !pr.was_packed {
 			fmt.eprintfln("frame %d was not packed", pr.id)
@@ -337,27 +373,30 @@ pack_atlas :: proc(frames: []^image.Image) -> Atlas {
 		}
 		idx := int(pr.id)
 		frame := frames[idx]
-		fw := frame.width
+		trim := trims[idx]
-		fh := frame.height
+		tx, ty, tw, th := trim[0], trim[1], trim[2], trim[3]
 		dst_x := int(pr.x)
 		dst_y := int(pr.y)
 
 		src := bytes.buffer_to_bytes(&frame.pixels)
-		for y in 0 ..< fh {
+		src_w := int(frame.width)
-			src_row := src[y * fw * 4:(y + 1) * fw * 4]
+		for y in 0 ..< th {
+			src_row := src[((ty + y) * src_w + tx) * 4:][:tw * 4]
 			dst_i := ((dst_y + y) * atlas_w + dst_x) * 4
 			copy(pixels[dst_i:], src_row)
 		}
 
-		rects[idx] = {dst_x, dst_y, fw, fh}
+		rects[idx] = {dst_x, dst_y, tw, th}
 	}
 
 	fmt.printfln("packed atlas %dx%d", atlas_w, atlas_h)
 	return Atlas {
-		pixels = pixels,
+		pixels       = pixels,
-		width  = atlas_w,
+		width        = atlas_w,
-		height = atlas_h,
+		height       = atlas_h,
-		rects  = rects,
+		rects        = rects,
+		source_sizes = source_sizes,
+		trim_offsets = trim_offsets,
 	}
 }
 
@@ -422,8 +461,8 @@ build_char_def :: proc(
 			r := atlas.rects[slot]
 			frame_defs[i] = Frame_Def {
 				rect        = r,
-				source_size = {r[2], r[3]},
+				source_size = atlas.source_sizes[slot],
-				trim_offset = {0, 0}, // no trimming in v1
+				trim_offset = atlas.trim_offsets[slot],
 			}
 		}
 

assets_baked/characters/toad/toad.char.json

@@ -14,274 +14,274 @@
             "frames": [
                 {
                     "rect": [
-                        0,
+                        1253,
-                        0,
+                        630,
-                        268,
+                        204,
-                        326
+                        311
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        14
                     ]
                 },
                 {
                     "rect": [
-                        269,
+                        1256,
                         0,
-                        268,
+                        218,
-                        326
+                        314
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        10
                     ]
                 },
                 {
                     "rect": [
-                        538,
+                        1458,
-                        0,
+                        630,
-                        268,
+                        231,
-                        326
+                        310
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        8
                     ]
                 },
                 {
                     "rect": [
-                        807,
+                        643,
-                        0,
+                        943,
-                        268,
+                        243,
-                        326
+                        295
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        10,
-                        0
+                        7
                     ]
                 },
                 {
                     "rect": [
-                        1076,
+                        881,
-                        0,
+                        1245,
-                        268,
+                        254,
-                        326
+                        278
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        11,
-                        0
+                        8
-                    ]
-                },
-                {
-                    "rect": [
-                        1345,
-                        0,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
-                    ]
-                },
-                {
-                    "rect": [
-                        1614,
-                        0,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
                     ]
                 },
                 {
                     "rect": [
                         0,
-                        327,
+                        944,
-                        268,
+                        247,
-                        326
+                        288
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        10,
-                        0
+                        7
                     ]
                 },
                 {
                     "rect": [
-                        269,
+                        1669,
-                        327,
+                        941,
-                        268,
+                        236,
-                        326
+                        305
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        8
-                    ]
-                },
-                {
-                    "rect": [
-                        538,
-                        327,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
-                    ]
-                },
-                {
-                    "rect": [
-                        807,
-                        327,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
-                    ]
-                },
-                {
-                    "rect": [
-                        1076,
-                        327,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
-                    ]
-                },
-                {
-                    "rect": [
-                        1345,
-                        327,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
-                    ]
-                },
-                {
-                    "rect": [
-                        1614,
-                        327,
-                        268,
-                        326
-                    ],
-                    "source_size": [
-                        268,
-                        326
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
                     ]
                 },
                 {
                     "rect": [
                         0,
-                        654,
+                        316,
-                        268,
+                        223,
-                        326
+                        313
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        9
                     ]
                 },
                 {
                     "rect": [
-                        269,
+                        1458,
-                        654,
+                        941,
-                        268,
+                        210,
-                        326
+                        310
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
-                        0,
+                        9,
-                        0
+                        13
                     ]
                 },
                 {
                     "rect": [
-                        538,
+                        224,
-                        654,
+                        316,
-                        268,
+                        211,
-                        326
+                        313
                     ],
                     "source_size": [
                         268,
                         326
                     ],
                     "trim_offset": [
+                        11,
+                        11
+                    ]
+                },
+                {
+                    "rect": [
+                        1032,
+                        630,
+                        220,
+                        311
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        13,
+                        7
+                    ]
+                },
+                {
+                    "rect": [
+                        1032,
+                        942,
+                        228,
+                        302
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        16,
+                        4
+                    ]
+                },
+                {
+                    "rect": [
                         0,
-                        0
+                        1233,
+                        237,
+                        286
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        18,
+                        2
+                    ]
+                },
+                {
+                    "rect": [
+                        643,
+                        1239,
+                        237,
+                        286
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        18,
+                        2
+                    ]
+                },
+                {
+                    "rect": [
+                        414,
+                        943,
+                        228,
+                        302
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        16,
+                        4
+                    ]
+                },
+                {
+                    "rect": [
+                        1690,
+                        630,
+                        220,
+                        310
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        13,
+                        7
+                    ]
+                },
+                {
+                    "rect": [
+                        436,
+                        316,
+                        210,
+                        313
+                    ],
+                    "source_size": [
+                        268,
+                        326
+                    ],
+                    "trim_offset": [
+                        11,
+                        11
                     ]
                 }
             ]
@@ -292,290 +292,290 @@
             "frames": [
                 {
                     "rect": [
-                        807,
+                        414,
-                        654,
+                        630,
-                        213,
+                        205,
-                        319
+                        312
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        6,
-                        0
+                        7
                     ]
                 },
                 {
                     "rect": [
-                        1021,
+                        647,
-                        654,
+                        316,
-                        213,
+                        206,
-                        319
+                        313
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        5,
-                        0
+                        6
                     ]
                 },
                 {
                     "rect": [
-                        1235,
+                        854,
-                        654,
+                        316,
-                        213,
+                        206,
-                        319
+                        313
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        5,
-                        0
+                        6
                     ]
                 },
                 {
                     "rect": [
-                        1449,
+                        1684,
-                        654,
+                        0,
-                        213,
+                        207,
-                        319
+                        314
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        4,
-                        0
+                        5
                     ]
                 },
                 {
                     "rect": [
-                        1663,
+                        1256,
-                        654,
+                        315,
-                        213,
+                        207,
-                        319
+                        314
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        4,
-                        0
+                        5
                     ]
                 },
                 {
                     "rect": [
-                        807,
+                        420,
-                        974,
+                        0,
-                        213,
+                        208,
-                        319
+                        315
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        3,
-                        0
+                        4
                     ]
                 },
                 {
                     "rect": [
-                        1021,
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-                        319
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                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        3,
-                        0
+                        4
                     ]
                 },
                 {
                     "rect": [
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-                        319
+                        315
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
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-                        0
+                        3
-                    ]
-                },
-                {
-                    "rect": [
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-                    "trim_offset": [
-                        0,
-                        0
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-                },
-                {
-                    "rect": [
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-                    "source_size": [
-                        213,
-                        319
-                    ],
-                    "trim_offset": [
-                        0,
-                        0
                     ]
                 },
                 {
                     "rect": [
                         0,
-                        981,
+                        0,
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-                        319
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                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
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+                        2,
-                        0
+                        3
                     ]
                 },
                 {
                     "rect": [
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-                        319
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                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        2,
-                        0
+                        3
                     ]
                 },
                 {
                     "rect": [
-                        428,
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+                        0,
-                        213,
+                        208,
-                        319
+                        315
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        3,
-                        0
+                        3
                     ]
                 },
                 {
                     "rect": [
-                        642,
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-                        1294,
+                        0,
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+                        208,
-                        319
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                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        3,
-                        0
+                        4
                     ]
                 },
                 {
                     "rect": [
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+                        1464,
-                        1294,
+                        315,
-                        213,
+                        207,
-                        319
+                        314
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        4,
-                        0
+                        5
                     ]
                 },
                 {
                     "rect": [
-                        1070,
+                        1672,
-                        1294,
+                        315,
-                        213,
+                        207,
-                        319
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                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        4,
-                        0
+                        5
                     ]
                 },
                 {
                     "rect": [
-                        1284,
+                        0,
-                        1294,
+                        630,
-                        213,
+                        206,
-                        319
+                        313
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        5,
-                        0
+                        6
                     ]
                 },
                 {
                     "rect": [
-                        1498,
+                        207,
-                        1294,
+                        630,
-                        213,
+                        206,
-                        319
+                        313
                     ],
                     "source_size": [
                         213,
                         319
                     ],
                     "trim_offset": [
-                        0,
+                        5,
-                        0
+                        6
+                    ]
+                },
+                {
+                    "rect": [
+                        620,
+                        630,
+                        205,
+                        312
+                    ],
+                    "source_size": [
+                        213,
+                        319
+                    ],
+                    "trim_offset": [
+                        6,
+                        7
+                    ]
+                },
+                {
+                    "rect": [
+                        826,
+                        630,
+                        205,
+                        312
+                    ],
+                    "source_size": [
+                        213,
+                        319
+                    ],
+                    "trim_offset": [
+                        6,
+                        7
                     ]
                 }
             ]

engine/app.odin

@@ -1,6 +1,7 @@
 package engine
 
 import "core:fmt"
+import "core:mem"
 import "core:path/filepath"
 import sdl "vendor:sdl3"
 
@@ -10,7 +11,14 @@ Vertex :: struct {
 }
 
 SPRITE_VERT_COUNT :: 6
-VERTEX_BUFFER_SIZE :: SPRITE_VERT_COUNT * size_of(Vertex)
+MAX_SPRITES :: 128
+SPRITE_VERTS_SIZE :: SPRITE_VERT_COUNT * size_of(Vertex)
+VERTEX_BUFFER_SIZE :: MAX_SPRITES * SPRITE_VERTS_SIZE
+
+Queued_Sprite :: struct {
+	texture: ^sdl.GPUTexture,
+	verts:   [SPRITE_VERT_COUNT]Vertex,
+}
 
 App :: struct {
 	window:            ^sdl.Window,
@@ -25,6 +33,9 @@ App :: struct {
 	swapchain_h:       u32,
 	vertex_buffer:     ^sdl.GPUBuffer,
 	transfer_buffer:   ^sdl.GPUTransferBuffer,
+	draw_list:         [dynamic]Queued_Sprite,
+	clear_color:       sdl.FColor,
+	camera:            Camera,
 }
 
 Shader_Backend :: enum {
@@ -112,10 +123,16 @@ init :: proc(app: ^App, title: cstring, width, height: i32) -> bool {
 		return false
 	}
 
+	app.draw_list = make([dynamic]Queued_Sprite)
+
+	app.camera = camera_default()
+
 	return true
 }
 
 shutdown :: proc(app: ^App) {
+	delete(app.draw_list)
+
 	if app.device != nil {
 		ok := sdl.WaitForGPUIdle(app.device)
 		if !ok {
@@ -164,9 +181,13 @@ events :: proc() -> bool {
 	return true
 }
 
-begin_frame :: proc(app: ^App, clear: sdl.FColor = {0.12, 0.12, 0.16, 1}) {
+begin_frame :: proc(app: ^App, clear_color: sdl.FColor = {0.12, 0.12, 0.16, 1}) {
-	app.cmd = sdl.AcquireGPUCommandBuffer(app.device)
+	clear(&app.draw_list)
+	app.clear_color = clear_color
+	app.render_pass = nil
+	app.swapchain_texture = nil
 
+	app.cmd = sdl.AcquireGPUCommandBuffer(app.device)
 	if app.cmd == nil {
 		fmt.eprintfln("AcquireGPUCommandBuffer failed: %s", sdl.GetError())
 		return
@@ -181,36 +202,104 @@ begin_frame :: proc(app: ^App, clear: sdl.FColor = {0.12, 0.12, 0.16, 1}) {
 	)
 
 	if !ok || app.swapchain_texture == nil {
+		app.swapchain_texture = nil
 		return
 	}
+}
+
+end_frame :: proc(app: ^App) {
+	if app.cmd == nil {
+		clear(&app.draw_list)
+		return
+	}
+
+	cmd := app.cmd
+	defer {
+		app.render_pass = nil
+		app.swapchain_texture = nil
+		app.cmd = nil
+		clear(&app.draw_list)
+	}
+
+	if app.swapchain_texture == nil {
+		if !sdl.SubmitGPUCommandBuffer(cmd) {
+			fmt.eprintfln("SubmitGPUCommandBuffer failed")
+		}
+		return
+	}
+
+	n := len(app.draw_list)
+	if n > 0 {
+		map_ptr := sdl.MapGPUTransferBuffer(app.device, app.transfer_buffer, false)
+		if map_ptr == nil {
+			fmt.eprintfln("MapGPUTransferBuffer failed: %s", sdl.GetError())
+			if !sdl.SubmitGPUCommandBuffer(cmd) {
+				fmt.eprintfln("SubmitGPUCommandBuffer failed")
+			}
+			return
+		}
+
+		for i in 0 ..< n {
+			q := &app.draw_list[i]
+			offset := i * SPRITE_VERTS_SIZE
+			mem.copy(
+				rawptr(uintptr(map_ptr) + uintptr(offset)),
+				raw_data(q.verts[:]),
+				SPRITE_VERTS_SIZE,
+			)
+		}
+		sdl.UnmapGPUTransferBuffer(app.device, app.transfer_buffer)
+
+		copy_pass := sdl.BeginGPUCopyPass(cmd)
+		src := sdl.GPUTransferBufferLocation {
+			transfer_buffer = app.transfer_buffer,
+			offset          = 0,
+		}
+		dst := sdl.GPUBufferRegion {
+			buffer = app.vertex_buffer,
+			offset = 0,
+			size   = u32(n * SPRITE_VERTS_SIZE),
+		}
+		sdl.UploadToGPUBuffer(copy_pass, src, dst, false)
+		sdl.EndGPUCopyPass(copy_pass)
+	}
 
 	color_info := sdl.GPUColorTargetInfo {
 		texture     = app.swapchain_texture,
-		clear_color = clear,
+		clear_color = app.clear_color,
 		load_op     = .CLEAR,
 		store_op    = .STORE,
 	}
-
+	app.render_pass = sdl.BeginGPURenderPass(cmd, &color_info, 1, nil)
-	app.render_pass = sdl.BeginGPURenderPass(app.cmd, &color_info, 1, nil)
-
 	sdl.BindGPUGraphicsPipeline(app.render_pass, app.pipeline)
-}
 
-end_frame :: proc(app: ^App) {
+	i := 0
-	if app.render_pass != nil {
+	for i < n {
-		sdl.EndGPURenderPass(app.render_pass)
+		run := texture_run_len(app.draw_list[:], i)
-		app.render_pass = nil
+		q0 := app.draw_list[i]
-	}
 
-	if app.cmd != nil {
+		sampler_binding := sdl.GPUTextureSamplerBinding {
-		ok := sdl.SubmitGPUCommandBuffer(app.cmd)
+			texture = q0.texture,
-		if !ok {
+			sampler = app.sampler,
-			fmt.eprintfln("SubmitGPUCommandBuffer failed")
 		}
-		app.cmd = nil
+		sdl.BindGPUFragmentSamplers(app.render_pass, 0, &sampler_binding, 1)
-	}
 
-	app.swapchain_texture = nil
+		vb_binding := sdl.GPUBufferBinding {
+			buffer = app.vertex_buffer,
+			offset = u32(i * SPRITE_VERTS_SIZE),
+		}
+		sdl.BindGPUVertexBuffers(app.render_pass, 0, &vb_binding, 1)
+
+		sdl.DrawGPUPrimitives(app.render_pass, u32(run * SPRITE_VERT_COUNT), 1, 0, 0)
+
+		i += run
+	}
+	sdl.EndGPURenderPass(app.render_pass)
+	app.render_pass = nil
+
+	if !sdl.SubmitGPUCommandBuffer(cmd) {
+		fmt.eprintfln("SubmitGPUCommandBuffer failed")
+	}
 }
 
 load_gpu_shader :: proc(
@@ -338,3 +427,17 @@ create_sprite_pipeline :: proc(app: ^App) -> ^sdl.GPUGraphicsPipeline {
 
 	return pipeline
 }
+
+texture_run_len :: proc(list: []Queued_Sprite, start: int) -> int {
+	if start < 0 || start >= len(list) do return 0
+
+	tex := list[start].texture
+	n := 1
+
+	for i in start + 1 ..< len(list) {
+		if list[i].texture != tex do break
+		n += 1
+	}
+
+	return n
+}

engine/camera.odin

@@ -0,0 +1,17 @@
+package engine
+
+Camera :: struct {
+	position: Vec2,
+	anchor:   Vec2,
+}
+
+camera_default :: proc() -> Camera {
+	return Camera{position = {0, 0}, anchor = {0.5, 0.5}}
+}
+
+world_to_screen :: proc(cam: Camera, world: Vec2, viewport: Vec2) -> Vec2 {
+	return {
+		world.x - cam.position.x + viewport.x * cam.anchor[0],
+		world.y - cam.position.y + viewport.y * cam.anchor[1],
+	}
+}

engine/character_data.odin

@@ -210,6 +210,22 @@ character_clip :: proc(data: ^Character_Data, clip_name: string) -> (clip: Clip_
 	return character, true
 }
 
+character_frame :: proc(
+	data: ^Character_Data,
+	clip_name: string,
+	frame_index: int,
+) -> (
+	frame: Frame_Def,
+	ok: bool,
+) {
+	if data == nil do return {}, false
+	clip, found := data.def.clips[clip_name]
+	if !found || frame_index < 0 || frame_index >= len(clip.frames) {
+		return {}, false
+	}
+	return clip.frames[frame_index], true
+}
+
 character_frame_rect :: proc(
 	data: ^Character_Data,
 	clip_name: string,
@@ -218,10 +234,7 @@ character_frame_rect :: proc(
 	rect: [4]int,
 	ok: bool,
 ) {
-	clip, found := data.def.clips[clip_name]
+	frame, found := character_frame(data, clip_name, frame_index)
-	if !found || frame_index < 0 || frame_index >= len(clip.frames) {
+	if !found do return {}, false
-		return {}, false
+	return frame.rect, true
-	}
-
-	return clip.frames[frame_index].rect, true
 }

engine/input.odin

@@ -0,0 +1,43 @@
+package engine
+
+import sdl "vendor:sdl3"
+
+Key :: enum {
+	A,
+	D,
+	Left,
+	Right,
+	Up,
+	Down,
+	Space,
+	N1,
+	N2,
+}
+
+key_down :: proc(key: Key) -> bool {
+	keys := sdl.GetKeyboardState(nil)
+	if keys == nil do return false
+
+	scan_code: sdl.Scancode
+	switch key {
+	case .A:
+		scan_code = .A
+	case .D:
+		scan_code = .D
+	case .Left:
+		scan_code = .LEFT
+	case .Right:
+		scan_code = .RIGHT
+	case .Up:
+		scan_code = .UP
+	case .Down:
+		scan_code = .DOWN
+	case .Space:
+		scan_code = .SPACE
+	case .N1:
+		scan_code = ._1
+	case .N2:
+		scan_code = ._2
+	}
+	return keys[scan_code]
+}

engine/sprite.odin

@@ -1,6 +1,5 @@
 package engine
 
-import "core:mem"
 import sdl "vendor:sdl3"
 
 Vec2 :: [2]f32
@@ -11,6 +10,7 @@ Sprite :: struct {
 	clip:     string,
 	frame:    int,
 	time:     f32,
+	flip_x:   bool,
 }
 
 spawn_sprite :: proc(
@@ -39,7 +39,6 @@ spawn_sprite :: proc(
 	return sprite
 }
 
-// stubbed for later
 update_sprite :: proc(sprite: ^Sprite, dt: f32) {
 	if sprite == nil || sprite.data == nil do return
 	if dt <= 0 do return
@@ -84,43 +83,65 @@ to_clip :: proc(px, py, sw, sh: f32) -> [2]f32 {
 }
 
 draw_sprite :: proc(app: ^App, sprite: ^Sprite) {
-	if app.render_pass == nil || app.cmd == nil || app.swapchain_texture == nil {
+	if app.cmd == nil || app.swapchain_texture == nil {
-		return // begin_frame may have skipped (minimized window, etc.)
+		return
 	}
 	if sprite == nil || sprite.data == nil || sprite.data.texture == nil {
 		return
 	}
+	if len(app.draw_list) >= MAX_SPRITES {
+		return
+	}
 
-	rect, ok := character_frame_rect(sprite.data, sprite.clip, sprite.frame)
+	frame, ok := character_frame(sprite.data, sprite.clip, sprite.frame)
 	if !ok {
 		return
 	}
 
-	fw := f32(rect[2])
+	src_w := f32(frame.source_size[0])
-	fh := f32(rect[3])
+	src_h := f32(frame.source_size[1])
+	if src_w <= 0 do src_w = f32(frame.rect[2])
+	if src_h <= 0 do src_h = f32(frame.rect[3])
 
-	// Feet-centered placement, same as renderer version
+	fw := f32(frame.rect[2])
-	x0_px := sprite.position.x - fw * 0.5
+	fh := f32(frame.rect[3])
-	y0_px := sprite.position.y - fh
+	trim_x := f32(frame.trim_offset[0])
+	trim_y := f32(frame.trim_offset[1])
+	pivot := sprite.data.def.pivot
+
+	viewport := Vec2{f32(app.swapchain_w), f32(app.swapchain_h)}
+	feet := world_to_screen(app.camera, sprite.position, viewport)
+
+	canvas_top := feet.y - src_h * pivot[1]
+	x0_px, y0_px: f32
+	if sprite.flip_x {
+		canvas_left := feet.x - (1.0 - pivot[0]) * src_w
+		x0_px = canvas_left + (src_w - trim_x - fw)
+		y0_px = canvas_top + trim_y
+	} else {
+		canvas_left := feet.x - src_w * pivot[0]
+		x0_px = canvas_left + trim_x
+		y0_px = canvas_top + trim_y
+	}
 	x1_px := x0_px + fw
 	y1_px := y0_px + fh
 
 	sw := f32(app.swapchain_w)
 	sh := f32(app.swapchain_h)
-	p0 := to_clip(x0_px, y0_px, sw, sh) // top-left
+	p0 := to_clip(x0_px, y0_px, sw, sh)
-	p1 := to_clip(x1_px, y0_px, sw, sh) // top-right
+	p1 := to_clip(x1_px, y0_px, sw, sh)
-	p2 := to_clip(x1_px, y1_px, sw, sh) // bottom-right
+	p2 := to_clip(x1_px, y1_px, sw, sh)
-	p3 := to_clip(x0_px, y1_px, sw, sh) // bottom-left
+	p3 := to_clip(x0_px, y1_px, sw, sh)
 
 	tex_w := f32(sprite.data.width)
 	tex_h := f32(sprite.data.height)
-	u0 := f32(rect[0]) / tex_w
+	u0 := f32(frame.rect[0]) / tex_w
-	v0 := f32(rect[1]) / tex_h
+	v0 := f32(frame.rect[1]) / tex_h
-	u1 := f32(rect[0] + rect[2]) / tex_w
+	u1 := f32(frame.rect[0] + frame.rect[2]) / tex_w
-	v1 := f32(rect[1] + rect[3]) / tex_h
+	v1 := f32(frame.rect[1] + frame.rect[3]) / tex_h
+	if sprite.flip_x do u0, u1 = u1, u0
 
-	// Two triangles: (0,1,2) and (0,2,3)
+	verts := [SPRITE_VERT_COUNT]Vertex {
-	verts := [6]Vertex {
 		{pos = p0, uv = {u0, v0}},
 		{pos = p1, uv = {u1, v0}},
 		{pos = p2, uv = {u1, v1}},
@@ -129,54 +150,7 @@ draw_sprite :: proc(app: ^App, sprite: ^Sprite) {
 		{pos = p3, uv = {u0, v1}},
 	}
 
-	map_ptr := sdl.MapGPUTransferBuffer(app.device, app.transfer_buffer, false)
+	append(&app.draw_list, Queued_Sprite{texture = sprite.data.texture, verts = verts})
-	if map_ptr == nil {
-		return
-	}
-	mem.copy(map_ptr, raw_data(verts[:]), size_of(verts))
-	sdl.UnmapGPUTransferBuffer(app.device, app.transfer_buffer)
-
-	// IMPORTANT: SDL does not allow beginning a copy pass while a render pass
-	// is active on the same command buffer. Upload on a separate command buffer.
-	copy_cmd := sdl.AcquireGPUCommandBuffer(app.device)
-	if copy_cmd == nil {
-		return
-	}
-	copy_pass := sdl.BeginGPUCopyPass(copy_cmd)
-
-	src := sdl.GPUTransferBufferLocation {
-		transfer_buffer = app.transfer_buffer,
-		offset          = 0,
-	}
-	dst := sdl.GPUBufferRegion {
-		buffer = app.vertex_buffer,
-		offset = 0,
-		size   = u32(size_of(verts)),
-	}
-	sdl.UploadToGPUBuffer(copy_pass, src, dst, false)
-	sdl.EndGPUCopyPass(copy_pass)
-	fence := sdl.SubmitGPUCommandBufferAndAcquireFence(copy_cmd)
-	if fence == nil {
-		return
-	}
-	defer sdl.ReleaseGPUFence(app.device, fence)
-	if !sdl.WaitForGPUFences(app.device, true, &fence, 1) {
-		return
-	}
-
-	sampler_binding := sdl.GPUTextureSamplerBinding {
-		texture = sprite.data.texture,
-		sampler = app.sampler,
-	}
-	sdl.BindGPUFragmentSamplers(app.render_pass, 0, &sampler_binding, 1)
-
-	vb_binding := sdl.GPUBufferBinding {
-		buffer = app.vertex_buffer,
-		offset = 0,
-	}
-	sdl.BindGPUVertexBuffers(app.render_pass, 0, &vb_binding, 1)
-
-	sdl.DrawGPUPrimitives(app.render_pass, 6, 1, 0, 0)
 }
 
 set_sprite_clip :: proc(sprite: ^Sprite, clip: string) {
@@ -191,3 +165,12 @@ set_sprite_clip :: proc(sprite: ^Sprite, clip: string) {
 	sprite.frame = 0
 	sprite.time = 0
 }
+
+sprite_quad_origin :: proc(position: Vec2, size: Vec2, pivot: [2]f32) -> Vec2 {
+	return {position.x - size.x * pivot[0], position.y - size.y * pivot[1]}
+}
+
+set_sprite_flip_x :: proc(sprite: ^Sprite, flip: bool) {
+	if sprite == nil do return
+	sprite.flip_x = flip
+}

engine/sprite_test.odin

@@ -19,3 +19,17 @@ to_clip_corners :: proc(t: ^testing.T) {
 	testing.expect_value(t, p[0], f32(0))
 	testing.expect_value(t, p[1], f32(0))
 }
+
+@(test)
+sprite_quad_origin_feet :: proc(t: ^testing.T) {
+	o := sprite_quad_origin({400, 500}, {100, 200}, {0.5, 1.0})
+	testing.expect_value(t, o.x, f32(350))
+	testing.expect_value(t, o.y, f32(300))
+}
+
+@(test)
+sprite_quad_origin_center :: proc(t: ^testing.T) {
+	o := sprite_quad_origin({400, 500}, {100, 200}, {0.5, 0.5})
+	testing.expect_value(t, o.x, f32(350))
+	testing.expect_value(t, o.y, f32(400))
+}

examples/camera_sandbox/main.odin

@@ -0,0 +1,58 @@
+package main
+
+import eng "pkg:engine"
+
+// Camera sandbox: toad stays put; arrows pan the camera. Space toggles follow mode.
+main :: proc() {
+	app: eng.App
+	if !eng.init(&app, "camera sandbox", 800, 600) do return
+	defer eng.shutdown(&app)
+
+	data, ok := eng.load_character_data(&app, "assets_baked/characters/toad/toad.char.json")
+	if !ok do return
+	defer eng.destroy_character_data(&app, &data)
+
+	toad := eng.spawn_sprite(&data, {0, 0}, "idle", 0)
+	app.camera.position = {0, -100}
+
+	follow := false
+	space_was_down := false
+	CAM_SPEED :: f32(300)
+
+	last := eng.now_seconds()
+
+	for eng.events() {
+		now := eng.now_seconds()
+		dt := f32(now - last)
+		last = now
+
+		space := eng.key_down(.Space)
+		if space && !space_was_down {
+			follow = !follow
+		}
+		space_was_down = space
+
+		if follow {
+			app.camera.position = toad.position - {0, 100}
+		} else {
+			if eng.key_down(.Left) || eng.key_down(.A) {
+				app.camera.position.x -= CAM_SPEED * dt
+			}
+			if eng.key_down(.Right) || eng.key_down(.D) {
+				app.camera.position.x += CAM_SPEED * dt
+			}
+			if eng.key_down(.Up) {
+				app.camera.position.y -= CAM_SPEED * dt
+			}
+			if eng.key_down(.Down) {
+				app.camera.position.y += CAM_SPEED * dt
+			}
+		}
+
+		eng.update_sprite(&toad, dt)
+
+		eng.begin_frame(&app)
+		eng.draw_sprite(&app, &toad)
+		eng.end_frame(&app)
+	}
+}

examples/clips/main.odin

@@ -0,0 +1,38 @@
+package main
+
+import eng "pkg:engine"
+
+// Clip switcher: 1 = idle, 2 = walk. No movement — animation policy only.
+main :: proc() {
+	app: eng.App
+	if !eng.init(&app, "clips", 800, 600) do return
+	defer eng.shutdown(&app)
+
+	data, ok := eng.load_character_data(&app, "assets_baked/characters/toad/toad.char.json")
+	if !ok do return
+	defer eng.destroy_character_data(&app, &data)
+
+	toad := eng.spawn_sprite(&data, {400, 500}, "idle", 0)
+	app.camera.position = toad.position - {0, 100}
+
+	last := eng.now_seconds()
+
+	for eng.events() {
+		now := eng.now_seconds()
+		dt := f32(now - last)
+		last = now
+
+		if eng.key_down(.N1) {
+			eng.set_sprite_clip(&toad, "idle")
+		}
+		if eng.key_down(.N2) {
+			eng.set_sprite_clip(&toad, "walk")
+		}
+
+		eng.update_sprite(&toad, dt)
+
+		eng.begin_frame(&app)
+		eng.draw_sprite(&app, &toad)
+		eng.end_frame(&app)
+	}
+}

examples/crowd/main.odin

@@ -0,0 +1,49 @@
+package main
+
+import eng "pkg:engine"
+
+// Many sprites sharing one Character_Data (Flyweight) — good batching demo.
+COUNT :: 24
+
+main :: proc() {
+	app: eng.App
+	if !eng.init(&app, "crowd", 800, 600) do return
+	defer eng.shutdown(&app)
+
+	data, ok := eng.load_character_data(&app, "assets_baked/characters/toad/toad.char.json")
+	if !ok do return
+	defer eng.destroy_character_data(&app, &data)
+
+	sprites: [COUNT]eng.Sprite
+	for i in 0 ..< COUNT {
+		col := i % 8
+		row := i / 8
+		pos := eng.Vec2 {
+			f32(120 + col * 80),
+			f32(280 + row * 120),
+		}
+		clip := "idle" if (i % 2) == 0 else "walk"
+		sprites[i] = eng.spawn_sprite(&data, pos, clip, i % 5)
+	}
+
+	// Look at the middle of the grid
+	app.camera.position = {400, 400}
+
+	last := eng.now_seconds()
+
+	for eng.events() {
+		now := eng.now_seconds()
+		dt := f32(now - last)
+		last = now
+
+		for &s in sprites {
+			eng.update_sprite(&s, dt)
+		}
+
+		eng.begin_frame(&app)
+		for &s in sprites {
+			eng.draw_sprite(&app, &s)
+		}
+		eng.end_frame(&app)
+	}
+}

examples/hello_sprite/main.odin

@@ -0,0 +1,34 @@
+package main
+
+import eng "pkg:engine"
+
+// Minimal: load one baked character and draw idle. No input, no camera follow.
+main :: proc() {
+	app: eng.App
+	if !eng.init(&app, "hello sprite", 800, 600) do return
+	defer eng.shutdown(&app)
+
+	data, ok := eng.load_character_data(&app, "assets_baked/characters/toad/toad.char.json")
+	if !ok do return
+	defer eng.destroy_character_data(&app, &data)
+
+	sprite := eng.spawn_sprite(&data, {400, 500}, "idle", 0)
+
+	// Screen-centered framing without gameplay camera follow:
+	// treat spawn position as world; look slightly above feet.
+	app.camera.position = sprite.position - {0, 100}
+
+	last := eng.now_seconds()
+
+	for eng.events() {
+		now := eng.now_seconds()
+		dt := f32(now - last)
+		last = now
+
+		eng.update_sprite(&sprite, dt)
+
+		eng.begin_frame(&app)
+		eng.draw_sprite(&app, &sprite)
+		eng.end_frame(&app)
+	}
+}

examples/toad/main.odin

@@ -15,12 +15,32 @@ main :: proc() {
 	toad := eng.spawn_sprite(&data, {400, 500}, "idle", 0)
 
 	last := eng.now_seconds()
+	SPEED :: f32(200)
 
 	for eng.events() {
 		now := eng.now_seconds()
 		dt := f32(now - last)
 		last = now
 
+		left := eng.key_down(.A) || eng.key_down(.Left)
+		right := eng.key_down(.D) || eng.key_down(.Right)
+
+		if left || right {
+			eng.set_sprite_clip(&toad, "walk")
+			if left {
+				toad.position.x -= SPEED * dt
+				toad.flip_x = true
+			}
+
+			if right {
+				toad.position.x += SPEED * dt
+				toad.flip_x = false
+			}
+		} else {
+			eng.set_sprite_clip(&toad, "idle")
+		}
+
+		app.camera.position = toad.position - {0, 100}
 		eng.update_sprite(&toad, dt)
 
 		eng.begin_frame(&app)