ebiten/shader.go

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// 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 (
"bytes"
"fmt"
"go/parser"
"go/token"
"github.com/hajimehoshi/ebiten/internal/graphics"
"github.com/hajimehoshi/ebiten/internal/mipmap"
"github.com/hajimehoshi/ebiten/internal/shader"
)
var shaderSuffix string
func init() {
shaderSuffix = `
var __textureDstSize vec2
func textureDstSize() vec2 {
return __textureDstSize
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}
`
for i := 0; i < graphics.ShaderImageNum; i++ {
shaderSuffix += fmt.Sprintf(`
var __textureSize%[1]d vec2
func texture%[1]dSize() vec2 {
return __textureSize%[1]d
}
`, i)
}
for i := 0; i < graphics.ShaderImageNum; i++ {
var offset string
if i >= 1 {
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shaderSuffix += fmt.Sprintf(`
var __textureOffset%[1]d vec2
`, i)
offset = fmt.Sprintf(" + __textureOffset%d", i)
}
// __t%d is a special variable for a texture variable.
shaderSuffix += fmt.Sprintf(`
func texture%[1]dAt(pos vec2) vec4 {
return texture2D(__t%[1]d, pos%[2]s)
}
`, i, offset)
}
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shaderSuffix += `
func __vertex(position vec2, texCoord vec2, color vec4) (vec4, vec2, vec4) {
return mat4(
2/textureDstSize().x, 0, 0, 0,
0, 2/textureDstSize().y, 0, 0,
0, 0, 1, 0,
-1, -1, 0, 1,
) * vec4(position, 0, 1), texCoord, color
}
`
}
type Shader struct {
shader *mipmap.Shader
}
func NewShader(src []byte) (*Shader, error) {
var buf bytes.Buffer
buf.Write(src)
buf.WriteString(shaderSuffix)
fs := token.NewFileSet()
f, err := parser.ParseFile(fs, "", buf.Bytes(), parser.AllErrors)
if err != nil {
return nil, err
}
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// TODO: Create a pseudo vertex entrypoint to treat the attribute values correctly.
s, err := shader.Compile(fs, f, "__vertex", "Fragment", graphics.ShaderImageNum)
if err != nil {
return nil, err
}
return &Shader{
shader: mipmap.NewShader(s),
}, nil
}
func (s *Shader) Dispose() {
s.shader.MarkDisposed()
s.shader = nil
}