mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-27 04:08:53 +01:00
116 lines
2.9 KiB
Go
116 lines
2.9 KiB
Go
/*
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Copyright 2014 Hajime Hoshi
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package opengl
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import (
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"errors"
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"fmt"
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"github.com/go-gl/gl"
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"github.com/hajimehoshi/ebiten/internal"
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)
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func orthoProjectionMatrix(left, right, bottom, top int) [4][4]float64 {
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e11 := float64(2) / float64(right-left)
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e22 := float64(2) / float64(top-bottom)
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e14 := -1 * float64(right+left) / float64(right-left)
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e24 := -1 * float64(top+bottom) / float64(top-bottom)
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return [4][4]float64{
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{e11, 0, 0, e14},
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{0, e22, 0, e24},
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{0, 0, 1, 0},
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{0, 0, 0, 1},
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}
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}
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type Framebuffer struct {
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framebuffer gl.Framebuffer
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width int
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height int
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flipY bool
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}
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func NewZeroFramebuffer(width, height int) (*Framebuffer, error) {
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r := &Framebuffer{
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width: width,
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height: height,
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flipY: true,
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}
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return r, nil
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}
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func NewFramebufferFromTexture(texture *Texture) (*Framebuffer, error) {
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framebuffer, err := createFramebuffer(texture.Native())
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if err != nil {
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return nil, err
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}
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w, h := texture.Size()
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return &Framebuffer{
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framebuffer: framebuffer,
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width: w,
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height: h,
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}, nil
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}
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func (f *Framebuffer) Size() (width, height int) {
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return f.width, f.height
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}
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func (f *Framebuffer) Dispose() {
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f.framebuffer.Delete()
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}
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func createFramebuffer(nativeTexture gl.Texture) (gl.Framebuffer, error) {
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framebuffer := gl.GenFramebuffer()
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framebuffer.Bind()
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gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, nativeTexture, 0)
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if gl.CheckFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE {
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return 0, errors.New("creating framebuffer failed")
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}
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return framebuffer, nil
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}
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func (f *Framebuffer) SetAsViewport() error {
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gl.Flush()
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f.framebuffer.Bind()
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err := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
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if err != gl.FRAMEBUFFER_COMPLETE {
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if gl.GetError() != 0 {
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return errors.New(fmt.Sprintf("glBindFramebuffer failed: %d", gl.GetError()))
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}
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return errors.New("glBindFramebuffer failed: the context is different?")
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}
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width := internal.NextPowerOf2Int(f.width)
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height := internal.NextPowerOf2Int(f.height)
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gl.Viewport(0, 0, width, height)
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return nil
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}
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func (f *Framebuffer) ProjectionMatrix() [4][4]float64 {
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width := internal.NextPowerOf2Int(f.width)
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height := internal.NextPowerOf2Int(f.height)
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m := orthoProjectionMatrix(0, width, 0, height)
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if f.flipY {
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m[1][1] *= -1
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m[1][3] += float64(f.height) / float64(internal.NextPowerOf2Int(f.height)) * 2
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}
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return m
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}
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