// updateBuffer fills the OpenGL buffer IF NEEDED.
// It updates the buffer if the bufferdataClean flag is false.
// It is safe to call this method every frame via the concrete classes method
// UpdateBuffer: most of the time it will just return immediately.
func (buffer *baseBuffer) update(vertexdata interface{}) {
if buffer.bufferdataClean {
return
}
if buffer.name == 0 {
panic("tried to update buffer 0")
}
// Convert the Go-friendly data into OpenGL-friendly data.
oldSize := len(buffer.bufferdata)
bufferdata := new(bytes.Buffer)
err := binary.Write(bufferdata, endianness, vertexdata)
if err != nil {
panic(err)
}
buffer.bufferdata = bufferdata.Bytes()
buffer.bufferdataClean = true
newSize := len(buffer.bufferdata)
// Should we make the buffer bigger?
needBigger := newSize > oldSize
buffer.bind()
if needBigger {
// (Re)allocate a buffer.
gl.BufferData(
buffer.target,
len(buffer.bufferdata),
buffer.bufferdata,
buffer.usage,
)
if err := CheckGlError(); err != nil {
err.Description = "gl.BufferData"
panic(err)
}
} else {
// Re-use existing buffer.
gl.BufferSubData(
buffer.target,
0,
len(buffer.bufferdata),
buffer.bufferdata,
)
if err := CheckGlError(); err != nil {
err.Description = "gl.BufferSubData"
panic(err)
}
}
buffer.unbind()
}
// buffer buffers the mesh data on the GPU.
// This calls glBufferData or glBufferSubData where appropriate.
func (a *Attr) buffer() {
switch v := a.data.(type) {
case []int8:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []uint8:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []int16:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []uint16:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []int32:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []uint32:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []float32:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
case []float64:
size := len(v) * a.stride
if size != a.gpuSize {
gl.BufferData(a.target, size, v, a.usage)
a.gpuSize = size
} else {
gl.BufferSubData(a.target, 0, size, v)
}
}
a.invalid = false
}