internal/cmd/convertshaders: replace fxc.exe with D3DCompile

D3DCompile successfully compiles shaders fxc.exe doesn't. As a bonus
the DirectX SDK is no longer required (it includes fxc.exe).

Signed-off-by: Elias Naur <mail@eliasnaur.com>

internal/cmd/convertshaders/hlsl_noop.go

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build !windows
+
+package main
+
+func compileHLSL(src, entry, profile string) ([]byte, error) {
+	return nil, nil
+}

internal/cmd/convertshaders/hlsl_windows.go

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package main
+
+import "gioui.org/internal/d3dcompile"
+
+func compileHLSL(src, entry, profile string) ([]byte, error) {
+	return d3dcompile.D3DCompile([]byte(src), entry, profile)
+}

internal/cmd/convertshaders/main.go

@@ -55,8 +55,6 @@ func generate() error {
 	if err != nil {
 		return err
 	}
-	fxc, err := exec.LookPath("fxc")
-	fxcFound := err == nil
 	shaders, err := filepath.Glob(filepath.Join(absShadersDir, "*"))
 	if err != nil {
 		return err
@@ -117,11 +115,9 @@ func generate() error {
 				return fmt.Errorf("unrecognized shader type %s", shader)
 			}
 			var hlslc []byte
-			if fxcFound {
-				hlslc, err = compileHLSL(tmp, fxc, hlsl, "main", hlslProf+"_4_0")
-				if err != nil {
-					return err
-				}
+			hlslc, err = compileHLSL(hlsl, "main", hlslProf+"_4_0")
+			if err != nil {
+				return err
 			}
 			// OpenGL 3.2 Core only accepts GLSL version 1.50, but is
 			// otherwise compatible with version 1.30.
@@ -310,26 +306,6 @@ func parseDataType(t string) (backend.DataType, int, error) {
 	}
 }
 
-func compileHLSL(tmp, fxc, src, entry, profile string) ([]byte, error) {
-	tmpfile := filepath.Join(tmp, "shader.hlsl")
-	if err := ioutil.WriteFile(tmpfile, []byte(src), 0644); err != nil {
-		return nil, err
-	}
-	outFile := filepath.Join(tmp, "shader.bin")
-	cmd := exec.Command(fxc,
-		"/T", profile,
-		"/E", entry,
-		"/nologo",
-		"/Fo", outFile,
-		tmpfile,
-	)
-	cmd.Stderr = os.Stderr
-	if err := cmd.Run(); err != nil {
-		return nil, err
-	}
-	return ioutil.ReadFile(outFile)
-}
-
 func convertShader(tmp, glslcc, path, lang, profile string, args *shaderArgs, flattenUBOs bool) (string, []byte, error) {
 	shaderTmpl, err := template.ParseFiles(path)
 	if err != nil {