ebiten/internal/graphics/framebuffer.go
2017-07-01 04:12:09 +09:00

75 lines
1.9 KiB
Go

// 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.
package graphics
import (
"github.com/hajimehoshi/ebiten/internal/opengl"
)
func orthoProjectionMatrix(left, right, bottom, top int) []float32 {
e11 := 2 / float32(right-left)
e22 := 2 / float32(top-bottom)
e14 := -1 * float32(right+left) / float32(right-left)
e24 := -1 * float32(top+bottom) / float32(top-bottom)
return []float32{
e11, 0, 0, 0,
0, e22, 0, 0,
0, 0, 1, 0,
e14, e24, 0, 1,
}
}
type framebuffer struct {
native opengl.Framebuffer
flipY bool
proMatrix []float32
offsetX float64
offsetY float64
}
func newFramebufferFromTexture(texture *texture) (*framebuffer, error) {
native, err := opengl.GetContext().NewFramebuffer(opengl.Texture(texture.native))
if err != nil {
return nil, err
}
return &framebuffer{
native: native,
}, nil
}
const viewportSize = 4096
func (f *framebuffer) setAsViewport() error {
width := viewportSize
height := viewportSize
return opengl.GetContext().SetViewport(f.native, width, height)
}
func (f *framebuffer) projectionMatrix(height int) []float32 {
if f.proMatrix != nil {
return f.proMatrix
}
m := orthoProjectionMatrix(0, viewportSize, 0, viewportSize)
if f.flipY {
m[4*1+1] *= -1
m[4*3+1] += float32(height) / float32(viewportSize) * 2
}
m[4*3+0] += float32(f.offsetX) / float32(viewportSize) * 2
m[4*3+1] += float32(f.offsetY) / float32(viewportSize) * 2
f.proMatrix = m
return f.proMatrix
}