Jump to content
  • Advertisement
Sign in to follow this  

OpenGL Texture Display Issues

This topic is 4009 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi all. Sorry if this is a beginner question, but I have not been able to find any solution to this problem, or indeed anyone else who has had the same problem. I have tried several times to display a texture on a simple polygon using OpenGL, but for some reason, no matter what image library I use, I have problems. The texture does not load, leaving the polygon a default white colour. I have tried with Cocoa image loading, SDL, and GLFW. I'm compiling on a PPC running Mac OS X, and I'm using XCode v2.4. Here is a sample of my OpenGL code:
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "GL/glfw.h"

#define S_WIDTH 640
#define S_HEIGHT 480

// Bad Global Variables:
//int width, height;													// Window dimensions
double t;																// Time (seconds)
GLuint texture;															// Texture reference

// Function prototypes:
void reSizeGLScene( GLsizei width, GLsizei height );
bool initGL();
bool loadTexture( const char* path );
bool drawGLScene();
void cleanUp();

int main( int argc, char** argv )
	// Initialize variables:
	bool status = true;		// Is the program okay?
	bool done = false;		// Is the program done?
	// Start up GLFW
	// Open up a window
	status = glfwOpenWindow(
		8, 8, 8, 8,
	// Exit if there is an error opening the window
	if ( !status )
		fprintf( stderr, "ERROR OPENING GLFW WINDOW\n" );
		return 1;
	// Set the window title
	glfwSetWindowTitle( "My OpenGL Program" );
	// Enable sticky keys
	glfwEnable( GLFW_STICKY_KEYS );
	loadTexture( "data/test.tga" );
	// Game loop:
	while ( !done )
		reSizeGLScene( S_WIDTH, S_HEIGHT );
		// Call the render function:
		status = drawGLScene();
		// Flip buffers:
		done = glfwGetKey( GLFW_KEY_ESC ) || !glfwGetWindowParam( GLFW_OPENED );
	// Clean up:
/*~~~~~~~~~~~ reSizeGLScene() ~~~~~~~~~~~~*/
/*  - Resize and initialize the GL window
void reSizeGLScene( GLsizei width, GLsizei height )
	// Make sure the height is non-zero
	if ( height < 1 )
		height = 1;
	// Set the viewport:
	glViewport( 0, 0, width, height );
	// Now set up the projection matrix:
	glMatrixMode( GL_PROJECTION );										// Change the matrix mode to projection
	glLoadIdentity();													// Identity Matrix
	gluPerspective( 65.0, (double)width/(double)height, 1.0, 100.0 );	// Set the perspective
	// Set up the modelview matrix:
	glMatrixMode( GL_MODELVIEW );										// Modelview matrix
	glLoadIdentity();													// Identity matrix
/*~~~~~~~~~~~~~~~ initGL() ~~~~~~~~~~~~~~~*/
/*  - Initializes OpenGL
bool initGL()
	glEnable( GL_TEXTURE_2D );											// Enable texture mapping
	glShadeModel( GL_SMOOTH );											// Use the smooth shader model
	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );								// Set a black background
	glClearDepth( 1.0f );												// Setup the depth buffer
	glEnable( GL_DEPTH_TEST );											// Enable depth testing
	glDepthFunc( GL_LEQUAL );											// The type of depth test to do
	glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );				// Really Nice perspective calculations
	return true;														// Return success
/*~~~~~~~~~~~~ loadTexture() ~~~~~~~~~~~~~*/
/*  - Initializes Textures
bool loadTexture( const char* path )
	glGenTextures( 0, &texture );
	glBindTexture( GL_TEXTURE_2D, texture );
	glfwLoadTexture2D( path, 0 );
	return true;
/*~~~~~~~~~~~~ drawGLScene() ~~~~~~~~~~~~~*/
/*  - Main OpenGL draw function
bool drawGLScene()
	// Now let's get the system time
	t = glfwGetTime();

	// Clear colour and depth buffers:
	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );				// Clear the screen and depth buffer
	glLoadIdentity();													// Reset the ModelView Matrix
	glTranslatef( 0.0f, 0.0f,-6.0f );									// Set the offset
	glEnable( GL_TEXTURE_2D );
	glBindTexture( GL_TEXTURE_2D, texture );							// Select texture
	fprintf( stderr, "Texture id: %d\n", texture );
	glBegin( GL_QUADS );
		glTexCoord2f( 0.0f, 0.0f ); glVertex3f(-2.0f, 2.0f, 0.0f );
		glTexCoord2f( 1.0f, 0.0f ); glVertex3f( 2.0f, 2.0f, 0.0f );
		glTexCoord2f( 1.0f, 1.0f ); glVertex3f( 2.0f,-2.0f, 0.0f );
		glTexCoord2f( 0.0f, 1.0f ); glVertex3f(-2.0f,-2.0f, 0.0f );
	glDisable( GL_TEXTURE_2D );
	return true;														// Return success
/*~~~~~~~~~~~~~~ cleanUp() ~~~~~~~~~~~~~~~*/
/*  - Clean everything up
void cleanUp()
I have already looked at several examples and tutorials. I suspect that the problem is probably in the draw function, but I can't seem to pinpoint the exact problem. While I have no error checking on my image file, it is a 256x256 targa file. It also has the correct filepath. Hopefully I'm not wasting your time with a stupid mistake, and thanks in advance for helping out.

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Advertisement

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!