ebiten/graphics/opengl/texture.go

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package opengl
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// #cgo LDFLAGS: -framework OpenGL
//
// #include <OpenGL/gl.h>
import "C"
import (
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"github.com/hajimehoshi/go-ebiten/graphics"
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"image"
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"unsafe"
)
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func nextPowerOf2(x uint64) uint64 {
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x -= 1
x |= (x >> 1)
x |= (x >> 2)
x |= (x >> 4)
x |= (x >> 8)
x |= (x >> 16)
x |= (x >> 32)
return x + 1
}
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func adjustPixels(width, height int, pixels []uint8) []uint8 {
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textureWidth := int(nextPowerOf2(uint64(width)))
textureHeight := int(nextPowerOf2(uint64(height)))
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if width == textureWidth && height == textureHeight {
return pixels
}
newPixels := make([]uint8, textureWidth*textureHeight*4)
for j := 0; j < height; j++ {
copy(newPixels[textureWidth*4*j:],
pixels[width*4*j:width*4*j+width*4])
}
return newPixels
}
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type Texture struct {
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id C.GLuint
width int
height int
textureWidth int
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textureHeight int
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framebuffer C.GLuint
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}
func (texture *Texture) ID() graphics.TextureID {
return graphics.TextureID(texture.id)
}
func (texture *Texture) Width() int {
return texture.width
}
func (texture *Texture) Height() int {
return texture.height
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}
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func createTexture(width, height int, pixels []uint8) *Texture {
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if pixels != nil {
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pixels = adjustPixels(width, height, pixels)
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}
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textureWidth := int(nextPowerOf2(uint64(width)))
textureHeight := int(nextPowerOf2(uint64(height)))
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texture := &Texture{
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id: 0,
width: width,
height: height,
textureWidth: textureWidth,
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textureHeight: textureHeight,
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}
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textureID := C.GLuint(0)
C.glGenTextures(1, (*C.GLuint)(&textureID))
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if textureID < 0 {
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panic("glGenTexture failed")
}
C.glPixelStorei(C.GL_UNPACK_ALIGNMENT, 4)
C.glBindTexture(C.GL_TEXTURE_2D, C.GLuint(textureID))
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ptr := unsafe.Pointer(nil)
if pixels != nil {
ptr = unsafe.Pointer(&pixels[0])
}
C.glTexImage2D(C.GL_TEXTURE_2D, 0, C.GL_RGBA,
C.GLsizei(textureWidth), C.GLsizei(textureHeight),
0, C.GL_RGBA, C.GL_UNSIGNED_BYTE, ptr)
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C.glTexParameteri(C.GL_TEXTURE_2D, C.GL_TEXTURE_MAG_FILTER, C.GL_LINEAR)
C.glTexParameteri(C.GL_TEXTURE_2D, C.GL_TEXTURE_MIN_FILTER, C.GL_LINEAR)
C.glBindTexture(C.GL_TEXTURE_2D, 0)
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texture.id = textureID
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return texture
}
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type textureError string
func (err textureError) Error() string {
return "Texture Error: " + string(err)
}
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func newRenderTarget(width, height int) *Texture {
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texture := createTexture(width, height, nil)
texture.framebuffer = createFramebuffer(texture.id)
return texture
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}
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func newTextureFromImage(img image.Image) (*Texture, error) {
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var pix []uint8
switch img.(type) {
case *image.RGBA:
pix = img.(*image.RGBA).Pix
case *image.NRGBA:
pix = img.(*image.NRGBA).Pix
default:
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return nil, textureError("image format must be RGBA or NRGBA")
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}
size := img.Bounds().Size()
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return createTexture(size.X, size.Y, pix), nil
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}
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func newRenderTargetWithFramebuffer(width, height int,
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framebuffer C.GLuint) *Texture {
return &Texture{
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id: 0,
width: width,
height: height,
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textureWidth: int(nextPowerOf2(uint64(width))),
textureHeight: int(nextPowerOf2(uint64(height))),
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framebuffer: framebuffer,
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}
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}
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func createFramebuffer(textureID C.GLuint) C.GLuint {
framebuffer := C.GLuint(0)
C.glGenFramebuffers(1, &framebuffer)
origFramebuffer := C.GLint(0)
C.glGetIntegerv(C.GL_FRAMEBUFFER_BINDING, &origFramebuffer)
C.glBindFramebuffer(C.GL_FRAMEBUFFER, framebuffer)
C.glFramebufferTexture2D(C.GL_FRAMEBUFFER, C.GL_COLOR_ATTACHMENT0,
C.GL_TEXTURE_2D, textureID, 0)
C.glBindFramebuffer(C.GL_FRAMEBUFFER, C.GLuint(origFramebuffer))
if C.glCheckFramebufferStatus(C.GL_FRAMEBUFFER) !=
C.GL_FRAMEBUFFER_COMPLETE {
panic("creating framebuffer failed")
}
return framebuffer
}