ebiten/internal/graphics/framebuffer.go

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// Copyright 2014 Hajime Hoshi
//
// 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.
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package graphics
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import (
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"image/color"
"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
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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)
e22 := float64(2) / float64(top-bottom)
e14 := -1 * float64(right+left) / float64(right-left)
e24 := -1 * float64(top+bottom) / float64(top-bottom)
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return &[4][4]float64{
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{e11, 0, 0, e14},
{0, e22, 0, e24},
{0, 0, 1, 0},
{0, 0, 0, 1},
}
}
type Framebuffer struct {
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native opengl.Framebuffer
width int
height int
flipY bool
proMatrix *[4][4]float64
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}
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func NewZeroFramebuffer(c *opengl.Context, width, height int) (*Framebuffer, error) {
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f := &Framebuffer{
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width: width,
height: height,
flipY: true,
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}
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return f, nil
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}
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func NewFramebufferFromTexture(c *opengl.Context, texture *Texture) (*Framebuffer, error) {
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native, err := c.NewFramebuffer(opengl.Texture(texture.native))
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if err != nil {
return nil, err
}
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f := &Framebuffer{
native: native,
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width: texture.width,
height: texture.height,
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}
return f, nil
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}
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func (f *Framebuffer) Dispose(c *opengl.Context) error {
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// Don't delete the default framebuffer.
if f.native == opengl.ZeroFramebuffer {
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return nil
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}
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c.DeleteFramebuffer(f.native)
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return nil
}
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const viewportSize = 4096
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func (f *Framebuffer) setAsViewport(c *opengl.Context) error {
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width := viewportSize
height := viewportSize
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return c.SetViewport(f.native, width, height)
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}
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func (f *Framebuffer) projectionMatrix() *[4][4]float64 {
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if f.proMatrix != nil {
return f.proMatrix
}
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width := viewportSize
height := viewportSize
m := orthoProjectionMatrix(0, width, 0, height)
if f.flipY {
m[1][1] *= -1
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m[1][3] += float64(f.height) / float64(height) * 2
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}
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f.proMatrix = m
return f.proMatrix
}
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func (f *Framebuffer) Fill(context *opengl.Context, clr color.Color) error {
c := &fillCommand{
dst: f,
color: clr,
}
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theCommandQueue.Enqueue(c)
return nil
}
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func (f *Framebuffer) DrawTexture(context *opengl.Context, t *Texture, vertices []int16, geo, clr Matrix, mode opengl.CompositeMode) error {
c := &drawImageCommand{
dst: f,
src: t,
vertices: vertices,
geo: geo,
color: clr,
mode: mode,
}
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theCommandQueue.Enqueue(c)
// Drawing a texture to the default buffer must be the last command.
// TODO(hajimehoshi): This seems a little hacky. Refactor.
if f.native == opengl.ZeroFramebuffer {
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if err := theCommandQueue.Flush(context); err != nil {
return err
}
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}
return nil
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}
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func (f *Framebuffer) Pixels(context *opengl.Context) ([]uint8, error) {
// Flush the enqueued commands so that pixels are certainly read.
if err := theCommandQueue.Flush(context); err != nil {
return nil, err
}
return context.FramebufferPixels(f.native, f.width, f.height)
}
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func (f *Framebuffer) ReplacePixels(context *opengl.Context, t *Texture, p []uint8) error {
c := &replacePixelsCommand{
dst: f,
texture: t,
pixels: p,
}
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theCommandQueue.Enqueue(c)
return nil
}