add shader backend + support for multiple shader formats

Makefile

@@ -0,0 +1,27 @@
+.PHONY: shaders-vulkan shaders-d3d12 shaders-metal shaders-all toad check help
+
+help:
+	@echo "Targets:"
+	@echo "  shaders-vulkan  Compile SPIR-V into shaders/vulkan/"
+	@echo "  shaders-d3d12   Compile DXIL into shaders/d3d12/ (needs shadercross)"
+	@echo "  shaders-metal   Compile MSL into shaders/metal/ (needs shadercross)"
+	@echo "  shaders-all     Build all shader backends"
+	@echo "  check           Typecheck examples/toad"
+	@echo "  toad            Run the toad example"
+
+shaders-vulkan:
+	./scripts/shaders_vulkan.sh
+
+shaders-d3d12:
+	./scripts/shaders_d3d12.sh
+
+shaders-metal:
+	./scripts/shaders_metal.sh
+
+shaders-all: shaders-vulkan shaders-d3d12 shaders-metal
+
+check:
+	odin check examples/toad -collection:pkg=.
+
+toad:
+	odin run examples/toad -collection:pkg=.