>Psychtoolbox>PsychDemos>OpenGL4MatlabDemos

DrawDots3DDemo – Show fast drawing of 3D dots.

Usage: DrawDots3DDemo([stereoMode=0][, multiSample=0]);

This demo shows how to use the moglDrawDots3D() function to draw 3D dots
in OpenGL 3D mode. The function is mostly equivalent to
Screen(‘DrawDots’) for drawing of 2D dots in regular 2D mode.

The first subdemo simply fills the whole 3D scene with uniformly sampled
random 3D dots, using the special sampling procedure
CreateUniformDotsIn3DFrustum() which was contributed by Diederick
Niehorster.

The second subdemo shows how to use a GLSL vertex shader on modern GPU’s
to speed up complex drawing of complex 3D dot fields. It shows a nicely
shaded, slowly rotating “Utah Teapot”. Below the teapot is a primitive
“sparkling fire” of 100 3D dots, which are lit by OpenGL and whose
positions are computed in Matlab/Octave on the CPU. The teapot also emits
a fountain of colorful particles from its nozzle. This fountain consists
of 10000 particles, and the particle trajectories are computed on the GPU
by use of a GLSL vertex shader. Please note that this subdemo may be
pretty boring, not showing the magic fountain, if your GPU doesn’t
support shaders.

The 3rd subdemo is a speed shootout: It draws the same fountain as demo
2, but as fast as it can, with sync of display updates to the vertical
retrace disabled. The fountain is drawn 3 times a 20 seconds duration.
First with purely Matlab computed trajectories, then with the same shader
as in demo 2, then again with the shader, but additionally applying
OpenGL display lists to store all data in the fast VRAM of the GPU to
gain an additional speedup. At the end of these three benchmark runs, the
demo will end and print out the average redraw rates attainable by the
three methods. On a modern system with a modern graphics card, you should
observe quite drastic speedups of GPU+VRAM vs. GPU vs. Matlab/CPU.

The 4th subdemo simulates a “warp-flight” by creating a particle fountain
that approaches the viewer, expanding while doing so.

Btw. if you are a proud owner of a good 3D stereo setup, or at least of
some anaglyph glasses, you should try the stereo display option as well,
e.g., stereoMode == 8 for red-blue anaglyphs.

Pressing the ESCape key continues the demo and progresses to next
subdemo. Mouse clicks will pause some demos, until another mouse click
continues the demo.

Optional parameter:

‘stereoMode’ if set to a non-zero value, will render at lest the 2nd demo
in a binocular stereo presentation mode, using the method specified in
the ‘stereoMode’ flag. See for example ImagingStereoDemo for available
modes.

‘multiSample’ if set to a non-zero value will enable multi-sample
anti-aliasing. This however usually doesn’t give good results with
smoothed 3D dots.