Add shader public APIs experimentally

Updates #1168

examples/shader/main.go

@@ -0,0 +1,94 @@
+// 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 example jsgo
+
+package main
+
+import (
+	"log"
+
+	"github.com/hajimehoshi/ebiten"
+)
+
+const (
+	screenWidth  = 640
+	screenHeight = 480
+)
+
+const shaderSrc = `package main
+
+func Vertex(position vec2, texCoord vec2, color vec4) vec4 {
+	return mat4(
+		2.0/640, 0, 0, 0,
+		0, 2.0/480, 0, 0,
+		0, 0, 1, 0,
+		-1, -1, 0, 1,
+	) * vec4(position, 0, 1)
+}
+
+func Fragment(position vec4) vec4 {
+	return vec4(position.x/640, position.y/480, 0, 1)
+}`
+
+type Game struct {
+	shader *ebiten.Shader
+}
+
+func (g *Game) Update(screen *ebiten.Image) error {
+	if g.shader == nil {
+		var err error
+		g.shader, err = ebiten.NewShader([]byte(shaderSrc))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (g *Game) Draw(screen *ebiten.Image) {
+	w, h := screen.Size()
+	vs := []ebiten.Vertex{
+		{
+			DstX: 0,
+			DstY: 0,
+		},
+		{
+			DstX: float32(w),
+			DstY: 0,
+		},
+		{
+			DstX: 0,
+			DstY: float32(h),
+		},
+		{
+			DstX: float32(w),
+			DstY: float32(h),
+		},
+	}
+	is := []uint16{0, 1, 2, 1, 2, 3}
+	screen.DrawTrianglesWithShader(vs, is, g.shader, nil)
+}
+
+func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return screenWidth, screenHeight
+}
+
+func main() {
+	ebiten.SetWindowSize(screenWidth, screenHeight)
+	ebiten.SetWindowTitle("Shader (Ebiten Demo)")
+	if err := ebiten.RunGame(&Game{}); err != nil {
+		log.Fatal(err)
+	}
+}

image.go

@@ -312,7 +312,6 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
 	bx1 := float32(b.Max.X)
 	by1 := float32(b.Max.Y)
 
-	// TODO: Should we use mipmap.verticesBackend?
 	vs := make([]float32, len(vertices)*graphics.VertexFloatNum)
 	for i, v := range vertices {
 		vs[i*graphics.VertexFloatNum] = v.DstX
@@ -334,6 +333,87 @@ func (i *Image) DrawTriangles(vertices []Vertex, indices []uint16, img *Image, o
 	i.buffered.DrawTriangles(img.buffered, vs, is, options.ColorM.impl, mode, filter, driver.Address(options.Address), nil, nil)
 }
 
+type DrawTrianglesWithShaderOptions struct {
+	Uniforms      []interface{}
+	CompositeMode CompositeMode
+}
+
+func (i *Image) DrawTrianglesWithShader(vertices []Vertex, indices []uint16, shader *Shader, options *DrawTrianglesWithShaderOptions) {
+	i.copyCheck()
+
+	if i.isDisposed() {
+		return
+	}
+
+	if i.isSubImage() {
+		panic("ebiten: render to a subimage is not implemented (DrawTriangles)")
+	}
+
+	if len(indices)%3 != 0 {
+		panic("ebiten: len(indices) % 3 must be 0")
+	}
+	if len(indices) > MaxIndicesNum {
+		panic("ebiten: len(indices) must be <= MaxIndicesNum")
+	}
+
+	if options == nil {
+		options = &DrawTrianglesWithShaderOptions{}
+	}
+
+	mode := driver.CompositeMode(options.CompositeMode)
+
+	us := []interface{}{}
+	var firstImage *Image
+	for _, v := range options.Uniforms {
+		switch v := v.(type) {
+		case *Image:
+			us = append(us, v.buffered)
+			if firstImage == nil {
+				firstImage = v
+			} else {
+				b := v.Bounds()
+				us = append(us, []float32{
+					float32(b.Min.X),
+					float32(b.Min.Y),
+					float32(b.Max.X),
+					float32(b.Max.Y),
+				})
+			}
+		default:
+			us = append(us, v)
+		}
+	}
+
+	var bx0, by0, bx1, by1 float32
+	if firstImage != nil {
+		b := firstImage.Bounds()
+		bx0 = float32(b.Min.X)
+		by0 = float32(b.Min.Y)
+		bx1 = float32(b.Max.X)
+		by1 = float32(b.Max.Y)
+	}
+
+	vs := make([]float32, len(vertices)*graphics.VertexFloatNum)
+	for i, v := range vertices {
+		vs[i*graphics.VertexFloatNum] = v.DstX
+		vs[i*graphics.VertexFloatNum+1] = v.DstY
+		vs[i*graphics.VertexFloatNum+2] = v.SrcX
+		vs[i*graphics.VertexFloatNum+3] = v.SrcY
+		vs[i*graphics.VertexFloatNum+4] = bx0
+		vs[i*graphics.VertexFloatNum+5] = by0
+		vs[i*graphics.VertexFloatNum+6] = bx1
+		vs[i*graphics.VertexFloatNum+7] = by1
+		vs[i*graphics.VertexFloatNum+8] = v.ColorR
+		vs[i*graphics.VertexFloatNum+9] = v.ColorG
+		vs[i*graphics.VertexFloatNum+10] = v.ColorB
+		vs[i*graphics.VertexFloatNum+11] = v.ColorA
+	}
+	is := make([]uint16, len(indices))
+	copy(is, indices)
+
+	i.buffered.DrawTriangles(nil, vs, is, nil, mode, driver.FilterNearest, driver.AddressClampToZero, shader.shader, us)
+}
+
 // SubImage returns an image representing the portion of the image p visible through r. The returned value shares pixels with the original image.
 //
 // The returned value is always *ebiten.Image.

shader.go

@@ -0,0 +1,40 @@
+// 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.
+
+package ebiten
+
+import (
+	"github.com/hajimehoshi/ebiten/internal/buffered"
+	"github.com/hajimehoshi/ebiten/internal/shader"
+)
+
+type Shader struct {
+	shader *buffered.Shader
+}
+
+func NewShader(src []byte) (*Shader, error) {
+	s, err := shader.Compile(src)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Shader{
+		shader: buffered.NewShader(s),
+	}, nil
+}
+
+func (s *Shader) Dispose() {
+	s.shader.MarkDisposed()
+	s.shader = nil
+}