gpu: setup OpenGL ES texture uniforms automatically from shader metadata

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

gpu/build.go

@@ -27,6 +27,12 @@ type shaderArgs struct {
 	Header         string
 }
 
+// TextureBinding matches gpu.TextureBinding.
+type TextureBinding struct {
+	Name    string
+	Binding int
+}
+
 // InputLocation matches gpu.InputLocation.
 type InputLocation struct {
 	Name          string
@@ -90,6 +96,7 @@ func generate() error {
 			hlsl        []byte
 			inputs      []InputLocation
 			uniforms    []UniformLocation
+			textures    []TextureBinding
 			uniformSize int
 		}
 		args := [nvariants]shaderArgs{
@@ -109,7 +116,7 @@ func generate() error {
 			}
 			// Make the GL ES 2 source compatible with desktop GL 3.
 			gles2 = "#version 100\n" + gles2
-			inputs, uniforms, uniformSize, err := parseReflection(reflect)
+			inputs, uniforms, textures, uniformSize, err := parseReflection(reflect)
 			if err != nil {
 				return err
 			}
@@ -138,6 +145,7 @@ func generate() error {
 			variants[i].hlsl = hlslc
 			variants[i].inputs = inputs
 			variants[i].uniforms = uniforms
+			variants[i].textures = textures
 			variants[i].uniformSize = uniformSize
 		}
 		name := filepath.Base(shader)
@@ -165,8 +173,17 @@ func generate() error {
 					fmt.Fprintf(&out, "{Name: %q, Type: %d, Size: %d, Offset: %d},\n", u.Name, u.Type, u.Size, u.Offset)
 				}
 				fmt.Fprintf(&out, "},\n")
+			}
+			if src.uniformSize != 0 {
 				fmt.Fprintf(&out, "UniformSize: %d,\n", src.uniformSize)
 			}
+			if len(src.textures) > 0 {
+				fmt.Fprintf(&out, "Textures: []TextureBinding{\n")
+				for _, t := range src.textures {
+					fmt.Fprintf(&out, "{Name: %q, Binding: %d},\n", t.Name, t.Binding)
+				}
+				fmt.Fprintf(&out, "},\n")
+			}
 			fmt.Fprintf(&out, "GLES2: %#v,\n", src.gles2)
 			fmt.Fprintf(&out, "/*\n%s\n*/\n", src.hlslSrc)
 			fmt.Fprintf(&out, "HLSL: %#v,\n", src.hlsl)
@@ -191,7 +208,7 @@ func generate() error {
 	return ioutil.WriteFile("shaders.go", gosrc, 0644)
 }
 
-func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, int, error) {
+func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, []TextureBinding, int, error) {
 	type InputReflection struct {
 		ID            int    `json:"id"`
 		Name          string `json:"name"`
@@ -214,9 +231,18 @@ func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, int,
 		Size    int                       `json:"block_size"`
 		Members []UniformMemberReflection `json:"members"`
 	}
+	type TextureReflection struct {
+		ID        int    `json:"id"`
+		Name      string `json:"name"`
+		Set       int    `json:"set"`
+		Binding   int    `json:"binding"`
+		Dimension string `json:"dimension"`
+		Format    string `json:"format"`
+	}
 	type shaderReflection struct {
 		Inputs         []InputReflection         `json:"inputs"`
 		UniformBuffers []UniformBufferReflection `json:"uniform_buffers"`
+		Textures       []TextureReflection       `json:"textures"`
 	}
 	type shaderMetadata struct {
 		VS shaderReflection `json:"vs"`
@@ -224,14 +250,14 @@ func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, int,
 	}
 	var reflect shaderMetadata
 	if err := json.Unmarshal(jsonData, &reflect); err != nil {
-		return nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
+		return nil, nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
 	}
 	var inputs []InputLocation
 	inputRef := reflect.VS.Inputs
 	for _, input := range inputRef {
 		dataType, dataSize, err := parseDataType(input.Type)
 		if err != nil {
-			return nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
+			return nil, nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
 		}
 		inputs = append(inputs, InputLocation{
 			Name:          input.Name,
@@ -255,7 +281,7 @@ func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, int,
 		for _, member := range block.Members {
 			dataType, size, err := parseDataType(member.Type)
 			if err != nil {
-				return nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
+				return nil, nil, nil, 0, fmt.Errorf("parseReflection: %v", err)
 			}
 			ublocks = append(ublocks, UniformLocation{
 				// Synthetic name generated by glslcc.
@@ -267,7 +293,18 @@ func parseReflection(jsonData []byte) ([]InputLocation, []UniformLocation, int,
 		}
 		blockOffset += block.Size
 	}
-	return inputs, ublocks, blockOffset, nil
+	textures := reflect.VS.Textures
+	if len(textures) == 0 {
+		textures = reflect.FS.Textures
+	}
+	var texBinds []TextureBinding
+	for _, texture := range textures {
+		texBinds = append(texBinds, TextureBinding{
+			Name:    texture.Name,
+			Binding: texture.Binding,
+		})
+	}
+	return inputs, ublocks, texBinds, blockOffset, nil
 }
 
 func parseDataType(t string) (DataType, int, error) {