// newFBO will generate a new Frame Buffer Object for use with the canvas
func newFBO(texture gl.Texture) (gl.Framebuffer, uint32) {
// get currently bound fbo to reset to it later
current_fbo := gl.GetBoundFramebuffer()
framebuffer := gl.CreateFramebuffer()
gl.BindFramebuffer(gl.FRAMEBUFFER, framebuffer)
if texture.Valid() {
gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0)
// Initialize the texture to transparent black.
gl.ClearColor(0.0, 0.0, 0.0, 0.0)
gl.Clear(gl.COLOR_BUFFER_BIT)
}
status := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
// unbind framebuffer
gl.BindFramebuffer(gl.FRAMEBUFFER, current_fbo)
return framebuffer, uint32(status)
}
// checkCreateStencil if a stencil is set on a canvas then we need to create
// some buffers to handle this.
func (canvas *Canvas) checkCreateStencil() bool {
// Do nothing if we've already created the stencil buffer.
if canvas.depth_stencil.Valid() {
return true
}
if gl_state.currentCanvas != canvas {
gl.BindFramebuffer(gl.FRAMEBUFFER, canvas.fbo)
}
format := gl.STENCIL_INDEX8
attachment := gl.STENCIL_ATTACHMENT
canvas.depth_stencil = gl.CreateRenderbuffer()
gl.BindRenderbuffer(gl.RENDERBUFFER, canvas.depth_stencil)
gl.RenderbufferStorage(gl.RENDERBUFFER, gl.Enum(format), int(canvas.width), int(canvas.height))
// Attach the stencil buffer to the framebuffer object.
gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.Enum(attachment), gl.RENDERBUFFER, canvas.depth_stencil)
gl.BindRenderbuffer(gl.RENDERBUFFER, gl.Renderbuffer{})
success := (gl.CheckFramebufferStatus(gl.FRAMEBUFFER) == gl.FRAMEBUFFER_COMPLETE)
// We don't want the stencil buffer filled with garbage.
if success {
gl.Clear(gl.STENCIL_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
} else {
gl.DeleteRenderbuffer(canvas.depth_stencil)
canvas.depth_stencil = gl.Renderbuffer{}
}
if gl_state.currentCanvas != nil && gl_state.currentCanvas != canvas {
gl.BindFramebuffer(gl.FRAMEBUFFER, gl_state.currentCanvas.fbo)
} else if gl_state.currentCanvas == nil {
gl.BindFramebuffer(gl.FRAMEBUFFER, getDefaultFBO())
}
return success
}
