in the example, the drawing is done in the default buffer and magically
read back into a bgl.Buffer object
here's what my code looks like
def render_preview(self, scene):
pixelCount = self.size_x * self.size_y
# Setup
buffer = bgl.Buffer(bgl.GL_FLOAT, [pixelCount, 4])
bgl.glClearColor(1.0, 1.0, 1.0, 1.0)
bgl.glClear(bgl.GL_COLOR_BUFFER_BIT or bgl.GL_DEPTH_BUFFER_BIT)
# i should have a white screen already
bgl.glBegin(bgl.GL_TRIANGLES)
bgl.glVertex3f(2.0, 2.0, 0.0)
bgl.glVertex3f(2.0, 0.0, 0.0)
bgl.glVertex3f(0.0, 2.0, 0.0)
bgl.glEnd()
# Read pixel data
bgl.glReadPixels(0, 0, self.size_x, self.size_y, bgl.GL_RGBA,
bgl.GL_FLOAT, buffer)
print(str(buffer))
# After printing, i get a series of 0s
I'm doing something blatantly wrong, aren't I? [?]
On Thu, Oct 23, 2014 at 5:31 PM, Dalai Felinto <[email protected]> wrote:
> Hi Khalifa,
>
> See if this sample file helps:
>
> https://svn.blender.org/svnroot/bf-blender/trunk/lib/tests/gameengine_visual/lampRGB.blend
>
> The code runs in the BGE (Blender Game Engine), but the BGE works the
> same for Blender and for the BGE.
>
> Apart from that BGL is simply a wrapper of OpenGL functions, so I
> presume the error is in your OpenGL (bgl) code.
>
> Regards,
> Dalai
> --
> blendernetwork.org/dalai-felinto
> www.dalaifelinto.com
>
>
> 2014-10-23 16:38 GMT+02:00 Khalifa Lame <[email protected]>:
> > glReadPixels() returns None. I'm sure it shouldn't be empty, I did some
> > clearing and drawing beforehand.
> > I even tried specifying the buffer to draw to using glDrawBuffer() and
> > glReadBuffer. Tried with GL_BACK and GL_AUX_BUFFERS. Both turn up empty.
> >
> > Is there something i'm missing?
> > Another weird thing, the preview window shows some colored dots when in
> > fact, the data fed to it was the empty result from glReadPixels().
> >
> > I'm new to openGL programming and even newer to bgl.
> >
> > --
> > khalibloo®
> >
> >
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> > http://lists.blender.org/mailman/listinfo/bf-python
> >
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