96 lines
2.7 KiB
Go
96 lines
2.7 KiB
Go
package canvas
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import (
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"image"
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"image/color"
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"unsafe"
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)
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var imageBufTex uint32
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var imageBuf []byte
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// GetImageData returns an RGBA image of the currently displayed image. The
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// alpha channel is always opaque
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func (cv *Canvas) GetImageData(x, y, w, h int) *image.RGBA {
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cv.activate()
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if x < 0 {
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w += x
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x = 0
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}
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if y < 0 {
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h += y
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y = 0
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}
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if w > cv.w {
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w = cv.w
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}
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if h > cv.h {
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h = cv.h
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}
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if len(imageBuf) < w*h*3 {
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imageBuf = make([]byte, w*h*3)
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}
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gli.ReadPixels(int32(x), int32(y), int32(w), int32(h), gl_RGB, gl_UNSIGNED_BYTE, gli.Ptr(&imageBuf[0]))
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rgba := image.NewRGBA(image.Rect(x, y, x+w, y+h))
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bp := 0
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for cy := y; cy < y+h; cy++ {
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for cx := x; cx < x+w; cx++ {
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rgba.SetRGBA(cx, y+h-1-cy, color.RGBA{R: imageBuf[bp], G: imageBuf[bp+1], B: imageBuf[bp+2], A: 255})
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bp += 3
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}
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}
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return rgba
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}
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// PutImageData puts the given image at the given x/y coordinates
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func (cv *Canvas) PutImageData(img *image.RGBA, x, y int) {
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cv.activate()
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gli.ActiveTexture(gl_TEXTURE0)
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if imageBufTex == 0 {
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gli.GenTextures(1, &imageBufTex)
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gli.BindTexture(gl_TEXTURE_2D, imageBufTex)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_LINEAR)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_S, gl_CLAMP_TO_EDGE)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_T, gl_CLAMP_TO_EDGE)
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} else {
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gli.BindTexture(gl_TEXTURE_2D, imageBufTex)
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}
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w, h := img.Bounds().Dx(), img.Bounds().Dy()
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if img.Stride == img.Bounds().Dx()*4 {
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gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(w), int32(h), 0, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&img.Pix[0]))
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} else {
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data := make([]uint8, 0, w*h*4)
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for cy := 0; cy < h; cy++ {
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start := cy * img.Stride
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end := start + w*4
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data = append(data, img.Pix[start:end]...)
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}
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gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(w), int32(h), 0, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&data[0]))
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}
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dx, dy := float32(x), float32(y)
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dw, dh := float32(w), float32(h)
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gli.BindBuffer(gl_ARRAY_BUFFER, buf)
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data := [16]float32{dx, dy, dx + dw, dy, dx + dw, dy + dh, dx, dy + dh,
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0, 0, 1, 0, 1, 1, 0, 1}
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gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)
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gli.UseProgram(ir.id)
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gli.Uniform1i(ir.image, 0)
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gli.Uniform2f(ir.canvasSize, float32(cv.fw), float32(cv.fh))
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gli.Uniform1f(ir.globalAlpha, 1)
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gli.VertexAttribPointer(ir.vertex, 2, gl_FLOAT, false, 0, 0)
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gli.VertexAttribPointer(ir.texCoord, 2, gl_FLOAT, false, 0, 8*4)
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gli.EnableVertexAttribArray(ir.vertex)
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gli.EnableVertexAttribArray(ir.texCoord)
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gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
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gli.DisableVertexAttribArray(ir.vertex)
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gli.DisableVertexAttribArray(ir.texCoord)
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}
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