internal/shaderir/msl: always use the same function names

internal/graphicsdriver/metal/shader_darwin.go

@@ -63,21 +63,16 @@ func (s *Shader) Dispose() {
 }
 
 func (s *Shader) init(device mtl.Device) error {
-	const (
-		v = "Vertex"
-		f = "Fragment"
-	)
-
-	src := msl.Compile(s.ir, v, f)
+	src := msl.Compile(s.ir)
 	lib, err := device.MakeLibrary(src, mtl.CompileOptions{})
 	if err != nil {
 		return fmt.Errorf("metal: device.MakeLibrary failed: %w, source: %s", err, src)
 	}
-	vs, err := lib.MakeFunction(v)
+	vs, err := lib.MakeFunction(msl.VertexName)
 	if err != nil {
 		return fmt.Errorf("metal: lib.MakeFunction for vertex failed: %w, source: %s", err, src)
 	}
-	fs, err := lib.MakeFunction(f)
+	fs, err := lib.MakeFunction(msl.FragmentName)
 	if err != nil {
 		return fmt.Errorf("metal: lib.MakeFunction for fragment failed: %w, source: %s", err, src)
 	}

internal/shader/shader_test.go

@@ -195,7 +195,7 @@ func TestCompile(t *testing.T) {
 			}
 
 			if tc.Metal != nil {
-				m := msl.Compile(s, "Vertex", "Fragment")
+				m := msl.Compile(s)
 				if got, want := metalNormalize(m), metalNormalize(string(tc.Metal)); got != want {
 					compare(t, "Metal", got, want)
 				}
@@ -203,7 +203,7 @@ func TestCompile(t *testing.T) {
 
 			// Just check that Compile doesn't cause panic.
 			// TODO: Should the results be tested?
-			msl.Compile(s, "Vertex", "Fragmentp")
+			msl.Compile(s)
 		})
 	}
 }

internal/shaderir/ir_test.go

@@ -1088,7 +1088,7 @@ void main(void) {
 					t.Errorf("%s fragment: got: %s, want: %s", tc.Name, got, want)
 				}
 			}
-			m := msl.Compile(&tc.Program, "Vertex", "Fragment")
+			m := msl.Compile(&tc.Program)
 			if tc.Metal != "" {
 				got := m
 				want := tc.Metal + "\n"

internal/shaderir/msl/msl.go

@@ -65,7 +65,12 @@ constexpr sampler texture_sampler{filter::nearest};`
 	return str
 }
 
-func Compile(p *shaderir.Program, vertex, fragment string) (shader string) {
+const (
+	VertexName   = "Vertex"
+	FragmentName = "Fragment"
+)
+
+func Compile(p *shaderir.Program) (shader string) {
 	c := &compileContext{
 		structNames: map[string]string{},
 	}
@@ -109,7 +114,7 @@ func Compile(p *shaderir.Program, vertex, fragment string) (shader string) {
 	if p.VertexFunc.Block != nil && len(p.VertexFunc.Block.Stmts) > 0 {
 		lines = append(lines, "")
 		lines = append(lines,
-			fmt.Sprintf("vertex Varyings %s(", vertex),
+			fmt.Sprintf("vertex Varyings %s(", VertexName),
 			"\tuint vid [[vertex_id]],",
 			"\tconst device Attributes* attributes [[buffer(0)]]")
 		for i, u := range p.Uniforms {
@@ -132,7 +137,7 @@ func Compile(p *shaderir.Program, vertex, fragment string) (shader string) {
 	if p.FragmentFunc.Block != nil && len(p.FragmentFunc.Block.Stmts) > 0 {
 		lines = append(lines, "")
 		lines = append(lines,
-			fmt.Sprintf("fragment float4 %s(", fragment),
+			fmt.Sprintf("fragment float4 %s(", FragmentName),
 			"\tVaryings varyings [[stage_in]]")
 		for i, u := range p.Uniforms {
 			lines[len(lines)-1] += ","