Use an in repo texture

Makefile

@@ -26,6 +26,7 @@ OBJDIR         = $(BUILDDIR)/obj
 COBJDIR        = $(OBJDIR)/c
 CXXOBJDIR      = $(OBJDIR)/cxx
 SHADER_OUTDIR  = $(BUILDDIR)/shaders
+ASSETS_DIR     = assets
 
 ifeq ($(WND_BKND), SDL)
 	CFLAGS += -DUSE_SDL_WINDOW_BACKEND
@@ -47,7 +48,7 @@ OUT_NAME       = main
 OUT            = $(BUILDDIR)/$(OUT_NAME)
 SHADER_OUT     = $(SHADER_OUTDIR)/shader.spv
 
-build: $(OUT) $(SHADER_OUT)
+build: $(OUT) $(SHADER_OUT) copy-assets
 
 $(OUT): $(OBJS)
 	$(CXX) $(LDFLAGS) -o "$@" $^ $(LDLIBS)
@@ -68,6 +69,9 @@ $(SHADER_OUT): $(SHADER_SRC)
 	@mkdir -p $(SHADER_OUTDIR)
 	$(SLANGC) $(SHADER_SRC) $(SLANGC_FLAGS) -o $(SHADER_OUT)
 
+copy-assets:
+	@cp -r $(ASSETS_DIR) $(BUILDDIR)
+
 run:
 	@cd $(BUILDDIR) && ./$(OUT_NAME)