CODEWITHSUNDEEP
c++imageqtopenglpbo
sacha legrand
sacha legrand

Reputation: 1

Video stream by GPU with a PBO load an ImageQT in OpenGL

I plan to develop a tool for realtime video manipulation using C++, QT 4.7.4 and OpenGL and i'm on visual studio 2008. I check many web site but my code doesn't work since I try with PBO. At the moment I imagine a following sequence of steps:

  1. load image file into QTimage
  2. copy data into PBO with glmapBuffer
  3. transfert into a texture with glTextSubImage2D

Is correct ?

And after succes with several image then I'll begin with video.

To see if I din't miss somthing a explaine my code: INIT I use glut so I initialised with :

glutInit(&iArgc, cppArgv); 
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE  | GLUT_ALPHA);
glutInitWindowSize(1000, 1000);
glutInitWindowPosition(500, 10);
glutCreateWindow("Texture"); 

glEnable(GL_TEXTURE_2D);

In my MAIN:

GLuint pboIds[2];
glGenBuffers(N_MAX_BUFFERS, pboIds);
//for two buffers
glBindBuffer(GL_PIXEL_PACK_BUFFER, pboIds[iBuffer]);
glBufferData(GL_PIXEL_PACK_BUFFER, DATA_SIZE, NULL, GL_STREAM_DRAW);

glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
glReadBuffer(GL_FRONT);

glGenTextures(1,&texture)

In a fonction loadImage I do the step 1:

QImage image;
image.load(name);
imageGL = QGLWidget::convertToGLFormat(image);
imageGL = (image.convertToFormat(QImage::Format_RGB888));//format is important

And the step 2 :

for (int iBuffer = 0; iBuffer < N_MAX_BUFFERS; ++iBuffer)
  {
    glBindBuffer(GL_PIXEL_PACK_BUFFER_EXT, pboIds[iBuffer]);
    glBufferData(GL_PIXEL_PACK_BUFFER_EXT, DATA_SIZE, NULL, GL_STREAM_DRAW);

    void * pPixelsPBO = glMapBuffer(GL_PIXEL_PACK_BUFFER_EXT, GL_WRITE_ONLY);
    // copy original image into the buffer (Step 2)
    if(pPixelsPBO)
    {
      pPixelsPBO = new unsigned char[imageGL.width() * imageGL.height() * 3];
      memcpy(pPixelsPBO, imageGL.bits(), DATA_SIZE);
    }
    glUnmapBuffer(GL_PIXEL_PACK_BUFFER_EXT
    glBindBuffer(GL_PIXEL_PACK_BUFFER_EXT, 0);
  }

And finally in the glutDisplayFunc():

//step 3
glBindTexture(GL_TEXTURE_2D, texture);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboIds[Index]);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, imageGL.width(), imageGL.height(), GL_RGB, GL_UNSIGNED_BYTE, 0);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
///

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glPushMatrix();
glBindTexture(GL_TEXTURE_2D, texture);
glColor4f(1, 1, 1, 1);

glBegin(GL_QUADS);

glTexCoord2i(0,0); glVertex2i(0,imageGL.height());
glTexCoord2i(0,1); glVertex2i(0,0);
glTexCoord2i(1,1); glVertex2i(imageGL.width(),0);
glTexCoord2i(1,0); glVertex2i(imageGL.width(),imageGL.height());
glEnd();

glBindTexture(GL_TEXTURE_2D, 0);
glDisable(GL_TEXTURE_2D);
glPopMatrix();
glutSwapBuffers();

//to load the next data from image 
// I do the step 1 et 2 at the end
LoadImg("./Code.jpg");

I get only an error on glTexSubImage2D() INVALID_OPERATION means generally format problem but I check many different format.

I don't know if i completly lost or if I close to succes.

Upvotes: 0

Views: 330

Answers (1)

sacha legrand
sacha legrand

Reputation: 1

ok I Call glTexImage2D only once to initialize the texture object in the loadImage fonction with : 

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR);//GL_NEAREST  GL_LINEAR
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8,imageGL.width(), imageGL.height(), 0, GL_RGB, GL_UNSIGNED_BYTE, (GLvoid*)imageGL.bits()); 
glBindTexture(GL_TEXTURE_2D, 0);

Upvotes: 0

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