Switching textures in opengl??

[Randulf]

Hi!
Im using qt and opengl to show data from a buffer as textures in opengl. The buffer has several sub images that I want to switch between. The problem is that It wont switch.
My QGLWidget has a method for updating the gl content where a pointer to the beginning of the buffer as argument. Then the textures made.

void GLWidget::setTexture(unsigned char *_data, float transfer, int dispChannelOne, int dispChannelTwo, int dispChannelThree)
{
	displayChannels = dispChannelOne + dispChannelTwo + dispChannelThree;
	channelOne = dispChannelOne;
 	channelTwo = dispChannelTwo;
	channelThree = dispChannelThree;
        textureData = _data;
 
	glEnable(GL_TEXTURE_2D);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 
	// Update the texture for channel one
	if(channelOne == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[0]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData+0*512*512);
	}
	// Update the texture for channel two
	if(channelTwo == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[1]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData + 1*512*512); //  + subchannels * widht * height
	}
	// Update the texture for channel three
	if(channelThree == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[2]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData + 2*512*512); //  + subchannels * widht * height
	}
	updateGL();
}
void GLWidget::paintGL()
{
 
	// Clear color buffer
	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
	glColorMask( GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE );
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	//glClear( GL_COLOR_BUFFER_BIT );
 
	// Set up the camera and projection
	// Select and setup the projection matrix
	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
 
	gluOrtho2D( -1.0f, 1.0f, -1.0f, 1.0f );
	glViewport( 0, 0, 512, 512);
	if(hasTexture) {
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glEnable(GL_TEXTURE_2D);
		glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
		if(channelOne == 1 && channelTwo == 0) 
			glBindTexture(GL_TEXTURE_2D, texture[0]);
		if(channelOne == 0 && channelTwo == 1) 
			glBindTexture(GL_TEXTURE_2D, texture[1]);
         }
	glBegin( GL_QUADS );
		glTexCoord2f( 1.0f, 0.0f );
		glVertex2f( -1.0f, -1.0f );
 
		glTexCoord2f( 0.0f, 0.0f );
		glVertex2f( 1.0f, -1.0f );
 
		glTexCoord2f( 0.0f, 1.0f );
		glVertex2f( 1.0f, 1.0f );
 
		glTexCoord2f( 1.0f, 1.0f );
		glVertex2f( -1.0f, 1.0f );
	glEnd();
}

void GLWidget::setTexture(unsigned char *_data, float transfer, int dispChannelOne, int dispChannelTwo, int dispChannelThree)
{
	displayChannels = dispChannelOne + dispChannelTwo + dispChannelThree;
	channelOne = dispChannelOne;
 	channelTwo = dispChannelTwo;
	channelThree = dispChannelThree;
        textureData = _data;

	glEnable(GL_TEXTURE_2D);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

	// Update the texture for channel one
	if(channelOne == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[0]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData+0*512*512);
	}
	// Update the texture for channel two
	if(channelTwo == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[1]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData + 1*512*512); //  + subchannels * widht * height
	}
	// Update the texture for channel three
	if(channelThree == 1) {
		glBindTexture(GL_TEXTURE_2D, texture[2]);
		glTexImage2D(GL_TEXTURE_2D, 0, 
					GL_LUMINANCE, 
					512, 512, 0, 
					GL_LUMINANCE, 
					GL_UNSIGNED_BYTE,
					textureData + 2*512*512); //  + subchannels * widht * height
	}
	updateGL();
}
void GLWidget::paintGL()
{
	
	// Clear color buffer
	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
	glColorMask( GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE );
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	//glClear( GL_COLOR_BUFFER_BIT );

	// Set up the camera and projection
	// Select and setup the projection matrix
	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();

	gluOrtho2D( -1.0f, 1.0f, -1.0f, 1.0f );
	glViewport( 0, 0, 512, 512);
	if(hasTexture) {
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glEnable(GL_TEXTURE_2D);
		glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
		if(channelOne == 1 && channelTwo == 0) 
			glBindTexture(GL_TEXTURE_2D, texture[0]);
		if(channelOne == 0 && channelTwo == 1) 
			glBindTexture(GL_TEXTURE_2D, texture[1]);
         }
	glBegin( GL_QUADS );
		glTexCoord2f( 1.0f, 0.0f );
		glVertex2f( -1.0f, -1.0f );

		glTexCoord2f( 0.0f, 0.0f );
		glVertex2f( 1.0f, -1.0f );

		glTexCoord2f( 0.0f, 1.0f );
		glVertex2f( 1.0f, 1.0f );

		glTexCoord2f( 1.0f, 1.0f );
		glVertex2f( -1.0f, 1.0f );
	glEnd();
}

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I can se the second texture but cannot switch to the first.

[wysota]

if(channelOne == 1 && channelTwo == 0)

if(channelOne == 1 && channelTwo == 0)

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Maybe this condition is never met?

[Randulf]

Found the problem, it only took me 4 hours : )

When generating the textures glTexParameteri must be set for all textures.