mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 21:32:20 +02:00
71 lines
1.8 KiB
Go
71 lines
1.8 KiB
Go
// Copyright 2014 Hajime Hoshi
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package graphics
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import (
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"github.com/hajimehoshi/ebiten/internal/opengl"
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)
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func orthoProjectionMatrix(left, right, bottom, top int) []float32 {
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e11 := 2 / float32(right-left)
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e22 := 2 / float32(top-bottom)
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e14 := -1 * float32(right+left) / float32(right-left)
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e24 := -1 * float32(top+bottom) / float32(top-bottom)
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return []float32{
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e11, 0, 0, 0,
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0, e22, 0, 0,
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0, 0, 1, 0,
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e14, e24, 0, 1,
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}
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}
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type framebuffer struct {
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native opengl.Framebuffer
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flipY bool
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proMatrix []float32
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}
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func newFramebufferFromTexture(context *opengl.Context, texture *texture) (*framebuffer, error) {
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native, err := context.NewFramebuffer(opengl.Texture(texture.native))
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if err != nil {
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return nil, err
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}
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return &framebuffer{
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native: native,
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}, nil
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}
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const viewportSize = 4096
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func (f *framebuffer) setAsViewport(context *opengl.Context) error {
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width := viewportSize
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height := viewportSize
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return context.SetViewport(f.native, width, height)
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}
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func (f *framebuffer) projectionMatrix(height int) []float32 {
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if f.proMatrix != nil {
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return f.proMatrix
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}
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m := orthoProjectionMatrix(0, viewportSize, 0, viewportSize)
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if f.flipY {
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m[4*1+1] *= -1
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m[4*3+1] += float32(height) / float32(viewportSize) * 2
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}
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f.proMatrix = m
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return f.proMatrix
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}
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