func (buf *TextureFramebuffer) StartSample(ctx gl.Context) {
buf.fbo.Bind(ctx, buf.withtex)
ctx.GetIntegerv(int32v4, gl.VIEWPORT)
ctx.Viewport(0, 0, buf.w, buf.h)
ctx.ClearColor(0, 0, 0, 0)
ctx.Clear(gl.COLOR_BUFFER_BIT)
}
func unproject(glctx gl.Context, x, y float32) (mgl32.Vec3, mgl32.Vec3) {
var wx, wy float32
var viewport [4]int32
glctx.GetIntegerv(viewport[:], gl.VIEWPORT)
wx = x
wy = float32(viewport[3]) - y
posStart, err := mgl32.UnProject(mgl32.Vec3{wx, wy, 0}, arcball.getMtx(), projectionMtx, int(viewport[0]), int(viewport[1]), int(viewport[2]), int(viewport[3]))
posEnd, err := mgl32.UnProject(mgl32.Vec3{wx, wy, 1}, arcball.getMtx(), projectionMtx, int(viewport[0]), int(viewport[1]), int(viewport[2]), int(viewport[3]))
if err != nil {
log.Printf("unable to unproject: %+v", err)
}
return posStart, posEnd
}