mirror of
https://github.com/hajimehoshi/ebiten.git
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86 lines
2.1 KiB
Go
86 lines
2.1 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 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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)
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type Filter int
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const (
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filterNearest Filter = gl.NEAREST
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filterLinear = gl.LINEAR
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)
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type Context struct {
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Nearest Filter
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Linear Filter
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}
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type Texture gl.Texture
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func (t Texture) Pixels(width, height int) ([]uint8, error) {
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// TODO: Use glGetTexLevelParameteri and GL_TEXTURE_WIDTH?
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pixels := make([]uint8, 4*width*height)
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gl.Texture(t).Bind(gl.TEXTURE_2D)
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gl.GetTexImage(gl.TEXTURE_2D, 0, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
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if e := gl.GetError(); e != gl.NO_ERROR {
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// TODO: Use glu.ErrorString
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return nil, errors.New(fmt.Sprintf("gl error: %d", e))
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}
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return pixels, nil
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}
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func (t Texture) Delete() {
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gl.Texture(t).Delete()
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}
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func NewContext() *Context {
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c := &Context{
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Nearest: filterNearest,
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Linear: filterLinear,
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}
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c.init()
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return c
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}
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func (c *Context) init() {
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gl.Init()
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gl.Enable(gl.TEXTURE_2D)
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// Textures' pixel formats are alpha premultiplied.
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gl.Enable(gl.BLEND)
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gl.BlendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA)
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}
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func (c *Context) NewTexture(width, height int, pixels []uint8, filter Filter) (Texture, error) {
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t := gl.GenTexture()
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if t < 0 {
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return 0, errors.New("glGenTexture failed")
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}
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gl.PixelStorei(gl.UNPACK_ALIGNMENT, 4)
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t.Bind(gl.TEXTURE_2D)
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defer gl.Texture(0).Bind(gl.TEXTURE_2D)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, int(filter))
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, int(filter))
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gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
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return Texture(t), nil
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}
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