[PyOpenGL-Users] glReadPixels not working in thread

[Shir G. <shi...@gm...>]

Hi,

My code works just fine without threading, but I’m trying to make it faster by processing the OpenGL data in another thread.

class Cube(app.Canvas):
*
*
*
	def finish(self):
    		im = gl.glReadPixels(0, 0, self.canvas_size[0], self.canvas_size[1], gl.GL_RGB, gl.GL_FLOAT)
    		rgb = np.copy(np.frombuffer(im, np.float32)).reshape(self.canvas_size + (3,))[::-1, :]  # Read buffer and flip Y
    		im = gl.glReadPixels(0, 0, self.canvas_size[0], self.canvas_size[1], gl.GL_DEPTH_COMPONENT, gl.GL_FLOAT)
    		dep = np.copy(np.frombuffer(im, np.float32)).reshape(self.canvas_size + (1,))[::-1, :]  # Read buffer and flip Y

    		# Convert z-buffer to depth map
    		mult = (self.clip_near * self.clip_far) / (self.clip_near - self.clip_far)
    		addi = self.clip_far / (self.clip_near - self.clip_far)
    		bg = dep == 1
    		dep = mult / (dep + addi)
    		dep[bg] = 0
    		return rgb, np.squeeze(dep)

	def next_batch(self, size):
		**** something
       		self.draw()
        	col, dep = self.finish()
		**** something

def load_data(o, size, q):
    while True:
        q.put(o.next_batch(size))

cube = Cube()
data_q = Queue()
p = Process(target=load_data, args=(cube, args.nof_load, data_q,))
p.start()
qg = data_q.get()

BUT when it reaches this line:
im = gl.glReadPixels(0, 0, self.canvas_size[0], self.canvas_size[1], gl.GL_RGB, gl.GL_FLOAT)
The program get stuck

Any idea why this happens when i use threading?

Thanks
Shir