ebiten/graphics/opengl/rendertarget.go
2014-12-08 00:53:23 +09:00

77 lines
1.9 KiB
Go

package opengl
import (
"fmt"
"github.com/go-gl/gl"
"github.com/hajimehoshi/ebiten/graphics/opengl/internal/shader"
)
func orthoProjectionMatrix(left, right, bottom, top int) [4][4]float64 {
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)
return [4][4]float64{
{e11, 0, 0, e14},
{0, e22, 0, e24},
{0, 0, 1, 0},
{0, 0, 0, 1},
}
}
type renderTarget struct {
framebuffer gl.Framebuffer
width int
height int
flipY bool
}
func newFramebuffer(nativeTexture gl.Texture) gl.Framebuffer {
framebuffer := gl.GenFramebuffer()
framebuffer.Bind()
gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0,
gl.TEXTURE_2D, nativeTexture, 0)
if gl.CheckFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE {
panic("creating framebuffer failed")
}
// Set this framebuffer opaque because alpha values on a target might be
// confusing.
gl.ClearColor(0, 0, 0, 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
return framebuffer
}
func (r *renderTarget) setAsViewport() {
gl.Flush()
r.framebuffer.Bind()
err := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
if err != gl.FRAMEBUFFER_COMPLETE {
panic(fmt.Sprintf("glBindFramebuffer failed: %d", err))
}
gl.BlendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ZERO, gl.ONE)
width := shader.AdjustSizeForTexture(r.width)
height := shader.AdjustSizeForTexture(r.height)
gl.Viewport(0, 0, width, height)
}
func (r *renderTarget) projectionMatrix() [4][4]float64 {
width := shader.AdjustSizeForTexture(r.width)
height := shader.AdjustSizeForTexture(r.height)
matrix := orthoProjectionMatrix(0, width, 0, height)
if r.flipY {
matrix[1][1] *= -1
matrix[1][3] += float64(r.height) / float64(shader.AdjustSizeForTexture(r.height)) * 2
}
return matrix
}
func (r *renderTarget) dispose() {
r.framebuffer.Delete()
}