ebiten/shader.go

144 lines
4.0 KiB
Go
Raw Normal View History

// 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 __imageDstTextureSize vec2
// imageSrcTextureSize returns the destination image's texture size in pixels.
func imageDstTextureSize() vec2 {
return __imageDstTextureSize
2020-06-23 18:41:27 +02:00
}
`
shaderSuffix += fmt.Sprintf(`
var __textureSizes [%[1]d]vec2
// imageSrcTextureSize returns the source image's texture size in pixels.
// As an image is a part of internal texture, the texture is usually bigger than the image.
// The texture's size is useful when you want to calculate pixels from texels.
func imageSrcTextureSize() vec2 {
return __textureSizes[0]
}
// The unit is the source texture's texel.
var __textureSourceOffsets [%[2]d]vec2
// The unit is the source texture's texel.
var __textureSourceRegionOrigin vec2
// The unit is the source texture's texel.
var __textureSourceRegionSize vec2
// imageSrcTextureRegion returns the source image's region (the origin and the size) on its texture.
// The unit is the source texture's texel.
//
// As an image is a part of internal texture, the image can be located at an arbitrary position on the texture.
func imageSrcTextureRegion() (vec2, vec2) {
return __textureSourceRegionOrigin, __textureSourceRegionSize
}
`, graphics.ShaderImageNum, graphics.ShaderImageNum-1)
for i := 0; i < graphics.ShaderImageNum; i++ {
pos := "pos"
if i >= 1 {
// Convert the position in texture0's texels to the target texture texels.
pos = fmt.Sprintf("(pos + __textureSourceOffsets[%d]) * __textureSizes[0] / __textureSizes[%d]", i-1, i)
}
// __t%d is a special variable for a texture variable.
shaderSuffix += fmt.Sprintf(`
func imageSrc%[1]dAt(pos vec2) vec4 {
// pos is the position in texels of the source texture (= 0th image's texture).
return texture2D(__t%[1]d, %[2]s)
}
func imageSrc%[1]dBoundsAt(pos vec2) vec4 {
// pos is the position in texels of the source texture (= 0th image's texture).
return texture2D(__t%[1]d, %[2]s) *
step(__textureSourceRegionOrigin.x, pos.x) *
(1 - step(__textureSourceRegionOrigin.x + __textureSourceRegionSize.x, pos.x)) *
step(__textureSourceRegionOrigin.y, pos.y) *
(1 - step(__textureSourceRegionOrigin.y + __textureSourceRegionSize.y, pos.y))
}
`, i, pos)
}
2020-07-26 07:33:37 +02:00
shaderSuffix += `
func __vertex(position vec2, texCoord vec2, color vec4) (vec4, vec2, vec4) {
return mat4(
2/imageDstTextureSize().x, 0, 0, 0,
0, 2/imageDstTextureSize().y, 0, 0,
2020-07-26 07:33:37 +02:00
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
}
const (
vert = "__vertex"
frag = "Fragment"
)
s, err := shader.Compile(fs, f, vert, frag, graphics.ShaderImageNum)
if err != nil {
return nil, err
}
if s.VertexFunc.Block == nil {
return nil, fmt.Errorf("ebiten: vertex shader entry point '%s' is missing", vert)
}
if s.FragmentFunc.Block == nil {
return nil, fmt.Errorf("ebiten: fragment shader entry point '%s' is missing", frag)
}
return &Shader{
shader: mipmap.NewShader(s),
}, nil
}
func (s *Shader) Dispose() {
s.shader.MarkDisposed()
s.shader = nil
}