Hi,
when I export my OpenGL animation to a QT movie at 60 FPS, everything works
very well. Now I would like to get a QT movie at 30 FPS and as I have been
told, I have created such a motion blur. In the QT I export, the resulting
movement is pretty good, but the colors of the QT frame-image look like
multiplied too much. They have been altered. The final image looks like
8-bit style, with stripes of colors instead of the original smooth blend.
May you please tell me what I do wrong?
-----------
I stretch my GL animation along the time, so if the original duration was
120 frames = 2 seconds at 60 FPS, now it is 240 frames (120 x 2). If I play
it now at 60 FPS, it runs slowly and smoothly. So I go to export this GL
animation.
I get 4 GL frames per each QT frame, so at the end 240 / 4 = 60 QT frames,
therefore again 2 seconds at 30 FPS. Well.
The great problem is how to mix these 4 GL frames. I use the accumulation
buffer. I init the glView with
-----------
NSOpenGLPFAAccumSize, 32,
...
glClearAccum(0.0, 0.0, 0.0, 0.0);
glClear(GL_ACCUM_BUFFER_BIT);
gMotionBlurFrames = 4;
-----------
Then in the drawRect loop I do:
-----------
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[objManager drawObjects];
[[self openGLContext] flushBuffer];
int xFrame = currentFrame % gMotionBlurFrames;
if(xFrame == 0) // first frame of 4
glAccum(GL_LOAD, (float)1.0f / gMotionBlurFrames);
else
glAccum(GL_ACCUM, 1.0f / gMotionBlurFrames);
if(xFrame != (gMotionBlurFrames - 1)){
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
else{
// last frame of 4
// at the 4th image taken, I get the accum buffer
// and I save it to a QT frame
glAccum(GL_RETURN, 1.0);
[self putOpenGLBufferToQTGWorld];
}
-----------
What do I miss?
Best Regards
--
Lorenzo
email: email@hidden
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