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sungsoo
04-06-2009, 01:26 PM
I try to implement real time transfunction operation; in that,
whenever user modifies transfer curve on screen, according to the modification, the displayed image is modified at the same time.

Firstly, I tested my program using small color image under not real time condition; in that, only if user release its mouse movement, this function is executed. At this time, this is working very well.

However, in the real time operation, it gives wrong value and even the image is disappeared at some point even though RGB values are not all zero(black).

I know I might make a really trivial but very important mistake. Can anybody give me any advice or suggestion? I attach part of my code.



void DisplayWindow::TransEdit()
{
//backupToFBO();

//0. setting parameter
float ColorFlag[4] = {0.0, 0.0, 0.0, 0.0};
if( selectedColor == 'r' ) ColorFlag[0] = 1.0;
else if( selectedColor == 'g' ) ColorFlag[1] = 1.0;
else if( selectedColor == 'b' ) ColorFlag[2] = 1.0;

//copy data to texture.
int num;
for(int i = 0; i < 256; i++) {
num = transFunc[0][i];
*(imgpixTrans + i) = (GLubyte) num;
}

//1. display on the frame buffer
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);

//one-to-one mapping from array index to texture coordinates
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0.0, imgx, 0.0, imgy);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glViewport(0, 0, imgx, imgy);

//2. setting input texture(s)
cgGLSetTextureParameter(originalParam, inputID);
cgGLEnableTextureParameter(originalParam);

glBindTexture(GL_TEXTURE_1D, transID);
glTexSubImage1D(GL_TEXTURE_1D, 0, 0, 256, GL_ALPHA, GL_UNSIGNED_BYTE, imgpixTrans);
cgGLSetTextureParameter(transcurve, transID);
cgGLEnableTextureParameter(transcurve);

//3. setting output texture(s)
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_RECTANGLE_NV, tempID, 0);
glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT);

//4. Bind fragment program: ready to use
cgGLBindProgram(TransProgram);

//5. give the argument to the fragment program
cgSetParameter4f(flag, ColorFlag[0], ColorFlag[1], ColorFlag[2], ColorFlag[3]);

//6. enable fragment program
cgGLEnableProfile(fProfile);
checkForCgError();

//7. render geometry
renderFBO();

//8. finish
cgGLDisableProfile(fProfile);

//9. GPU texture -> CPU arrays
glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
glReadPixels(0, 0, imgx, imgy, GL_RGBA, GL_UNSIGNED_BYTE, imgpixTemp);

//10. discard alpha in the array
Discard(imgpix, imgpixTemp);

//11. CPU array -> GPU texture
glBindTexture(GL_TEXTURE_RECTANGLE_NV, inputID);
glTexSubImage2D(GL_TEXTURE_RECTANGLE_NV, 0, 0, 0, imgx, imgy, GL_RGB, GL_UNSIGNED_BYTE, imgpix);

//12. unbind frame buffer
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

//13. update histogram and image
rgb2hsv();
gui->app->updateHistogramRGB(imgpix);
gui->app->updateHistogramHSV(imgpixHSV);
gui->app->Normalizing();

gui->displayWindow->redraw();
//gui->transFuncEditor->redraw();
}