examples/shader: Show an image

examples/shader/generate.go

@@ -15,3 +15,4 @@
 package main
 
 //go:generate file2byteslice -package=main -input=default.go -output=default_go.go -var=default_go
+//go:generate file2byteslice -package=main -input=image.go -output=image_go.go -var=image_go

examples/shader/image.go

@@ -0,0 +1,33 @@
+// Copyright 2020 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build ignore
+
+package main
+
+var Image texture2d
+
+func Vertex(position vec2, texCoord vec2, color vec4) (vec4, vec2) {
+	return mat4(
+		2/viewportSize().x, 0, 0, 0,
+		0, 2/viewportSize().y, 0, 0,
+		0, 0, 1, 0,
+		-1, -1, 0, 1,
+	) * vec4(position, 0, 1), texCoord
+}
+
+func Fragment(position vec4, tex vec2) vec4 {
+	// TODO: Instead of using texture2D directly, define and use special functions for Ebiten images.
+	return texture2D(Image, tex)
+}

examples/shader/image_go.go

@@ -0,0 +1,6 @@
+// Code generated by file2byteslice. DO NOT EDIT.
+// (gofmt is fine after generating)
+
+package main
+
+var image_go = []byte("// Copyright 2020 The Ebiten Authors\n//\n// Licensed under the Apache License, Version 2.0 (the \"License\");\n// you may not use this file except in compliance with the License.\n// You may obtain a copy of the License at\n//\n//     http://www.apache.org/licenses/LICENSE-2.0\n//\n// Unless required by applicable law or agreed to in writing, software\n// distributed under the License is distributed on an \"AS IS\" BASIS,\n// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n// See the License for the specific language governing permissions and\n// limitations under the License.\n\n// +build ignore\n\npackage main\n\nvar Image texture2d\n\nfunc Vertex(position vec2, texCoord vec2, color vec4) (vec4, vec2) {\n\treturn mat4(\n\t\t2/viewportSize().x, 0, 0, 0,\n\t\t0, 2/viewportSize().y, 0, 0,\n\t\t0, 0, 1, 0,\n\t\t-1, -1, 0, 1,\n\t) * vec4(position, 0, 1), texCoord\n}\n\nfunc Fragment(position vec4, tex vec2) vec4 {\n\t// TODO: Instead of using texture2D directly, define and use special functions for Ebiten images.\n\treturn texture2D(Image, tex)\n}\n")

examples/shader/main.go

@@ -17,9 +17,15 @@
 package main
 
 import (
+	"bytes"
+	"image"
+	_ "image/jpeg"
 	"log"
 
 	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+	"github.com/hajimehoshi/ebiten/examples/resources/images"
+	"github.com/hajimehoshi/ebiten/inpututil"
 )
 
 const (
@@ -27,8 +33,28 @@ const (
 	screenHeight = 480
 )
 
+var gophersImage *ebiten.Image
+
+func init() {
+	// Decode image from a byte slice instead of a file so that
+	// this example works in any working directory.
+	// If you want to use a file, there are some options:
+	// 1) Use os.Open and pass the file to the image decoder.
+	//    This is a very regular way, but doesn't work on browsers.
+	// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
+	//    This works even on browsers.
+	// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
+	//    This also works on browsers.
+	img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
+	if err != nil {
+		log.Fatal(err)
+	}
+	gophersImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
+}
+
 var shaderSrcs = [][]byte{
 	default_go,
+	image_go,
 }
 
 type Game struct {
@@ -39,6 +65,15 @@ type Game struct {
 
 func (g *Game) Update(screen *ebiten.Image) error {
 	g.time++
+	if inpututil.IsKeyJustPressed(ebiten.KeyDown) {
+		g.idx++
+		g.idx %= len(shaderSrcs)
+	}
+	if inpututil.IsKeyJustPressed(ebiten.KeyUp) {
+		g.idx += len(shaderSrcs) - 1
+		g.idx %= len(shaderSrcs)
+	}
+
 	if g.shaders == nil {
 		g.shaders = map[int]*ebiten.Shader{}
 	}
@@ -63,18 +98,26 @@ func (g *Game) Draw(screen *ebiten.Image) {
 		{
 			DstX: 0,
 			DstY: 0,
+			SrcX: 0,
+			SrcY: 0,
 		},
 		{
 			DstX: float32(w),
 			DstY: 0,
+			SrcX: float32(w),
+			SrcY: 0,
 		},
 		{
 			DstX: 0,
 			DstY: float32(h),
+			SrcX: 0,
+			SrcY: float32(h),
 		},
 		{
 			DstX: float32(w),
 			DstY: float32(h),
+			SrcX: float32(w),
+			SrcY: float32(h),
 		},
 	}
 	is := []uint16{0, 1, 2, 1, 2, 3}
@@ -82,11 +125,21 @@ func (g *Game) Draw(screen *ebiten.Image) {
 	cx, cy := ebiten.CursorPosition()
 
 	op := &ebiten.DrawTrianglesWithShaderOptions{}
+	switch g.idx {
+	case 0:
 		op.Uniforms = []interface{}{
-		float32(g.time) / 60,                // time
-		[]float32{float32(cx), float32(cy)}, // cursor
+			float32(g.time) / 60,                // Time
+			[]float32{float32(cx), float32(cy)}, // Cursor
+		}
+	default:
+		op.Uniforms = []interface{}{
+			gophersImage, // Image
+		}
 	}
 	screen.DrawTrianglesWithShader(vs, is, s, op)
+
+	msg := "Press Up/Down to switch the shader."
+	ebitenutil.DebugPrint(screen, msg)
 }
 
 func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {

internal/shader/shader.go

@@ -135,6 +135,7 @@ func Compile(fs *token.FileSet, f *ast.File, vertexEntry, fragmentEntry string)
 	// TODO: Resolve constants
 
 	// TODO: Make a call graph and reorder the elements.
+
 	return &s.ir, nil
 }
 

shader.go

@@ -28,7 +28,8 @@ var __viewportSize vec2
 
 func viewportSize() vec2 {
 	return __viewportSize
-}`
+}
+`
 
 type Shader struct {
 	shader *buffered.Shader
@@ -45,6 +46,7 @@ func NewShader(src []byte) (*Shader, error) {
 		return nil, err
 	}
 
+	// TODO: Create a pseudo vertex entrypoint to treat the attribute values correctly.
 	s, err := shader.Compile(fs, f, "Vertex", "Fragment")
 	if err != nil {
 		return nil, err