func (b *VertexBuffer) SetVertices(src []byte, usage Usage) error {
gl.VertexArray(0).Bind()
b.bind()
// set size of buffer and invalidate it
gl.BufferData(gl.ARRAY_BUFFER, len(src), nil, usage.gl())
if len(src) > 0 {
// if unmap returns false, the buffer we wrote to is no longer valid and we
// need to try again. though, this is apparently uncommon in modern
// drivers. this means it is not feasible to compute/copy vertices directly
// into the mapped buffer. however, it would be nice to provide a
// failure-capable API to do this.
const maxretries = 5
retries := 0
for ; retries < maxretries; retries++ {
ptr := gl.MapBuffer(gl.ARRAY_BUFFER, gl.WRITE_ONLY)
slicehdr := reflect.SliceHeader{
Data: uintptr(ptr),
Len: len(src),
Cap: len(src),
}
dest := *(*[]byte)(unsafe.Pointer(&slicehdr))
copy(dest, src)
if gl.UnmapBuffer(gl.ARRAY_BUFFER) {
break
}
}
if retries == maxretries {
return errMapBufferFailed
}
}
b.count = len(src) / b.format.Stride()
return nil
}
func (t *Texture) ReadTextureFromGPU() []byte {
t.Bind()
b := gl.GenBuffer()
b.Bind(gl.PIXEL_UNPACK_BUFFER)
gl.BufferData(gl.PIXEL_UNPACK_BUFFER, t.Width()*t.Height()*t.PixelSize(), 0, gl.STREAM_DRAW)
//gl.GetTexImage(t.target, 0, t.format, buffer)
b.Bind(gl.PIXEL_UNPACK_BUFFER)
gl.TexSubImage2D(t.target, 0, 0, 0, t.Width(), t.Height(), t.format, t.typ, unsafe.Pointer(uintptr(0)))
b.Bind(gl.PIXEL_UNPACK_BUFFER)
l := t.Width() * t.Height() * t.PixelSize()
gl.BufferData(gl.PIXEL_UNPACK_BUFFER, t.Width()*t.Height()*t.PixelSize(), 0, gl.STREAM_DRAW)
ptr := gl.MapBuffer(gl.PIXEL_UNPACK_BUFFER, gl.WRITE_ONLY)
var x []byte
s := (*reflect.SliceHeader)(unsafe.Pointer(&x))
s.Data = uintptr(ptr)
s.Len = l
s.Cap = l
gl.UnmapBuffer(gl.PIXEL_UNPACK_BUFFER)
return x
}
func (b *IndexBuffer) setIndices(copyTo func(unsafe.Pointer), usage Usage, size int) error {
gl.VertexArray(0).Bind()
b.bind()
gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, size, nil, usage.gl())
if size > 0 {
const maxretries = 5
retries := 0
for ; retries < maxretries; retries++ {
ptr := gl.MapBuffer(gl.ELEMENT_ARRAY_BUFFER, gl.WRITE_ONLY)
copyTo(ptr)
if gl.UnmapBuffer(gl.ELEMENT_ARRAY_BUFFER) {
break
}
}
if retries == maxretries {
return errMapBufferFailed
}
}
return nil
}