OpenGL texture mapping blank screen - c++

So I've been running through a tutorial on texture mapping in OpenGL and I'm using the function from the tutorial to attempt to map a texture in my own program.
I think I must be missing some necessary calls to something or going horribly wrong somewhere, but at the moment, I'm managing to achieve the black screen effect as per usual.
I've ran through this code and to my knowledge I see no reason why i should be getting a blank screen and was hoping anybody around here could spot where I'm going wrong
I'm using SDL just to clarify which I think might have some relevance to the problem maybe:
#include <iostream>
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
#include <GL/glu.h>
void Draw()
{
glTranslatef(320,240,0);
glBegin(GL_QUADS);
glColor3f(1,0,0);
glTexCoord2f(0,0); glVertex2f(0,0);
glTexCoord2f(100,0); glVertex2f(100,0);
glTexCoord2f(100,100); glVertex2f(100,100);
glTexCoord2f(0,100); glVertex2f(0,100);
glEnd();
glLoadIdentity();
}
void Init(void)
{
SDL_Init(SDL_INIT_EVERYTHING);
SDL_SetVideoMode(640,480,32,SDL_OPENGL);
SDL_WM_SetCaption("Texture Test", NULL);
}
void Set_States(void)
{
glClearColor(0,0,0,0);
glViewport(0, 0, 640, 480);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 640, 0, 480, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
GLuint LoadTextureRAW( const char * filename, int wrap )
{
GLuint texture;
int width, height;
BYTE * data;
FILE * file;
// open texture data
file = fopen( filename, "rb" );
if ( file == NULL ) return 0;
// allocate buffer
width = 256;
height = 256;
data = (BYTE*)malloc( width * height * 3 );
// read texture data
fread( data, width * height * 3, 1, file );
fclose( file );
// allocate a texture name
glGenTextures( 1, &texture );
// select our current texture
glBindTexture( GL_TEXTURE_2D, texture );
// select modulate to mix texture with color for shading
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
// when texture area is small, bilinear filter the closest mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_LINEAR_MIPMAP_NEAREST );
// when texture area is large, bilinear filter the first mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
// if wrap is true, the texture wraps over at the edges (repeat)
// ... false, the texture ends at the edges (clamp)
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
wrap ? GL_REPEAT : GL_CLAMP );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
wrap ? GL_REPEAT : GL_CLAMP );
// build our texture mipmaps
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,
GL_RGB, GL_UNSIGNED_BYTE, data );
// free buffer
free( data );
return texture;
}
int main (int argc, char ** argv)
{
GLuint texture;
SDL_Event event;
Init();
Set_States();
bool running = true;
glEnable( GL_TEXTURE_2D );
texture = LoadTextureRAW("texture.raw", 1);
glBindTexture( GL_TEXTURE_2D, texture );
while (running == true)
{
while (SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_QUIT: running = false; break;
}
glClear(GL_COLOR_BUFFER_BIT);
Draw();
SDL_GL_SwapBuffers();
}
}
SDL_Quit();
glDeleteTextures( 1, &texture );
return 0;
}

Well one problem is that you're not resetting your model-view matrix each time, so your quad gets quickly translated out of view (assuming it was in view to start with, which I haven't checked).

Give this a shot (texturing removed for brevity and lack of referenced file):
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
void Draw()
{
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 640, 0, 480, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glTranslatef(320,240,0);
glScalef( 100, 100, 0 );
glBegin(GL_QUADS);
glColor3f(1,0,0);
glTexCoord2f(0,0); glVertex2f(0,0);
glTexCoord2f(1,0); glVertex2f(1,0);
glTexCoord2f(1,1); glVertex2f(1,1);
glTexCoord2f(0,1); glVertex2f(0,1);
glEnd();
glPopMatrix();
}
int main (int argc, char ** argv)
{
SDL_Init(SDL_INIT_EVERYTHING);
SDL_SetVideoMode(640,480,32,SDL_OPENGL);
SDL_WM_SetCaption("Texture Test", NULL);
glClearColor(0,0,0,0);
glViewport(0, 0, 640, 480);
bool running = true;
while (running == true)
{
SDL_Event event;
while (SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_QUIT: running = false; break;
}
}
Draw();
SDL_GL_SwapBuffers();
}
SDL_Quit();
return 0;
}

Related

OpenGL and SDL_Image texture issue

I'm using glew 1.1.0, SDL_image 2.0 and mingw(Code::Blocks, Windows). I'm trying to import an .png file by using SDL_Image and to make it a texture and display to the screen i use OpenGL. When i run the program it displays a pure white square, it has the same width and height of the image im trying to import, but it's pure white. i looked over the code for about 30 minutes straight and the code looks fine, and it never gave me any errors execpt "Error initializing OpenGL! invalid value".
my main.cpp:
#include <GL/glew.h>
#include <SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <iostream>
#include <stdio.h>
#include <SDL_image.h>
#include <SDL_opengl.h>
using namespace std;
void init();
void Render();
bool ex;
bool akey;
SDL_Event e;
SDL_Window *win = NULL;
GLuint txID;
int x, y, w, h;
int main(int argc, char* args[])
{
init();
while(!ex)
{
while(SDL_PollEvent(&e) != 0)
{
if(e.type == SDL_QUIT)
{
ex = true;
}
Render();
}
}
}
void init()
{
SDL_Init(SDL_INIT_VIDEO);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 0);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
win = SDL_CreateWindow("Demo", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL);
SDL_GLContext cont = SDL_GL_CreateContext(win);
SDL_GL_SetSwapInterval(1);
glewInit();
glClear( GL_COLOR_BUFFER_BIT );
glViewport( 0.f, 0.f, 640, 480);
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( 0.0, 640, 480, 0.0, 1.0, -1.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glClearColor( 0.f, 0.f, 0.f, 1.f );
glEnable( GL_TEXTURE_2D );
glEnable(GL_BLEND);
SDL_Surface *sur = IMG_Load("ef.png");
w = 40;
h = 60;
glGenTextures( 1, &txID );
glBindTexture(GL_TEXTURE_2D, txID);
glTexImage2D(GL_TEXTURE_2D, 0, 4, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, sur->pixels);
GLenum error = glGetError();
if( error != GL_NO_ERROR )
{
printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) );
}
//Set texture parameters
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
//Unbind texture
glBindTexture(GL_TEXTURE_2D, NULL);
}
void Render()
{
glClear( GL_COLOR_BUFFER_BIT );
glLoadIdentity();
glTranslatef(20, 20, 0);
glBindTexture(GL_TEXTURE_2D, txID);
glBegin( GL_QUADS );
glTexCoord2f( 0.f, 0.f ); glVertex2f(0.f, 0.f);
glTexCoord2f( 1.f, 0.f ); glVertex2f(w, 0.f);
glTexCoord2f( 1.f, 1.f ); glVertex2f(w, h);
glTexCoord2f( 0.f, 1.f ); glVertex2f(0.f, h);
glEnd();
SDL_GL_SwapWindow(win);
}
This is the image I'm trying to load:
The program and the error, as you can see the white box is where the image is supposed to be.
You're getting an invalid value because you're passing 4 as the internalFormat. Passing 4 represents GL_TRIANGLES which isn't a valid format.
Check the documentation for valid formats.
You probably meant to pass GL_RGBA.
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, sur->pixels);
The weirdest part about this is i got to work on my old laptop
The reason it worked on your old laptop, is because the driver was being clever.
It still gives me the same error and still renders a pure white square
First of all instead of setting w and h yourself, you can get them from the SDL_Surface.
SDL_Surface *sur = IMG_Load("someimage.jpg");
GLuint txID = 0;
glGenTextures(1, &txID);
glBindTexture(GL_TEXTURE_2D, txID);
int mode = GL_RGB;
if(sur->format->BytesPerPixel == 4)
mode = GL_RGBA;
glTexImage2D(GL_TEXTURE_2D, 0, mode, sur->w, sur->h, 0, mode, GL_UNSIGNED_BYTE, sur->pixels);
I now noticed that you're targeting OpenGL 4.0. So the invalid value could also be caused by you trying to use the fixed-function pipeline, while having a OpenGL 4.0 context.
While I would recommend staying away from the fixed-function pipeline in general. Try requesting an OpenGL 2.0 context and see if that resolves the problem.
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 0);

Opening bmp image to texture in OpenGL

I'm having problems opening a bmp image to a texture using OpenGl
Here is the loadTexture func:
GLuint loadTexture() {
FILE *f;
int imageSize,rd;
f = fopen(filename, "rb");
if(f == 0){
printf("Couldn't open file\n");
exit(-1);
}
GLubyte header[54];
fread(header, 54,1,f);
if(header[0] != 'B' || header[1] != 'M'){
printf("File not bitmap\n");
exit(1);
}
dataPos = *(int*)&(header[0x0A]);
imageSize = *(int*)&(header[0x22]);
width = *(int*)&(header[0x12]);
height = *(int*)&(header[0x16]);
if (imageSize==0) imageSize=width*height*3;
if (dataPos==0) dataPos=54;
data = new unsigned char [imageSize];
fread(data,1,imageSize,f);
fclose(f);
GLuint textureID;
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP); return textureID;
}
The function always returns 0, but there is no error (I looked at glGetError() as well)
When trying to load the texture anyway:
glClear(GL_COLOR_BUFFER_BIT);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_REPLACE);
//BOTTOM LEFT - red
glBindTexture(GL_TEXTURE_2D,texture);
glViewport(0,0,256,256);
glBegin(GL_QUADS);
glTexCoord2f(0,0);
glVertex2f(-1,1);
glTexCoord2f(1,0);
glVertex2f(-1,-1);
glTexCoord2f(0,1);
glVertex2f(1,-1);
glTexCoord2f(1,1);
glVertex2f(1,1);
glEnd();
I get a white square and not the picture..
This is my init func:
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(512, 512);
glutCreateWindow("Sample");
glEnable(GL_TEXTURE_2D);
glOrtho(-1.0,1.0,-1.0,1.0,2.0,-2.0);
glClearColor(0,0,0,0);
texture = loadTexture();
printf("Texture: %d\n",texture);
glutDisplayFunc(mydisplay);
glutMainLoop();
Any thoughts?
You don't get a current GL context with GLUT until glutCreateWindow() successfully returns. glutInitDisplayMode() is not sufficient.
All the GL functions you call in loadTexture() require a current GL context to function.
Move texture = loadTexture(); to somewhere after glutCreateWindow() and before glutMainLoop();.
Also, if you're going to be using 3-component BGR/RGB make sure to use glPixelStorei() to set GL_UNPACK_ALIGNMENT to 1 (instead of the default 4) before your glTexImage2D() call.
Here's the simplest thing that works on my system:
// http://glew.sourceforge.net/
#include <GL/glew.h>
#include <GL/glut.h>
GLuint loadTexture()
{
const unsigned char data[] =
{
255, 0, 0, 0, 255, 0,
0, 0, 255, 255, 255, 255,
};
const GLsizei width = 2;
const GLsizei height = 2;
GLuint textureID = 0;
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);
return textureID;
}
GLuint texture = 0;
void display()
{
glClearColor( 0, 0, 0, 1 );
glClear( GL_COLOR_BUFFER_BIT );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( -2, 2, -2, 2, 2, -2 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D,texture);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_REPLACE);
glBegin(GL_QUADS);
glTexCoord2f( 0, 0 );
glVertex2i( -1, -1 );
glTexCoord2f( 1, 0 );
glVertex2i( 1, -1 );
glTexCoord2f( 1, 1 );
glVertex2i( 1, 1 );
glTexCoord2f( 0, 1 );
glVertex2i( -1, 1 );
glEnd();
glutSwapBuffers();
}
int main( int argc, char **argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
glutInitWindowSize( 640, 480 );
glutCreateWindow( "GLUT" );
glewInit();
texture = loadTexture();
glutDisplayFunc( display );
glutMainLoop();
return 0;
}

Displaying a loaded texture

I'm trying to make a game, it's 2D and has a moving player. I haven't worked with textures before and getting to display this texture correctly is very frustrating for me.
Current Output: http://puu.sh/7hTEL/64ac1529b1.jpg
My Image: http://puu.sh/7hUlM/3be59d6497.jpg
I just want that image to repeat itself (both x and y) over the background of the screen. at the moment I just have a fixed height / width for the game. It focuses on the player and the player is always moving in the x direction!
I have stripped down as most I can:
#include <iostream>
#include "snake.h"
#include <GL\glut.h>
GLuint texture = 0;
snake_t* snake = new snake_t();
GLuint LoadTexture( const char * filename, int width, int height )
{
GLuint texture;
unsigned char * data;
FILE * file;
//The following code will read in our RAW file
file = fopen( filename, "rb" );
if ( file == NULL ) return 0;
data = (unsigned char *)malloc( width * height * 3 );
fread( data, width * height * 3, 1, file );
fclose( file );
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
//even better quality, but this will do for now.
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR );
//to the edge of our shape.
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
//Generate the texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0,GL_RGB, GL_UNSIGNED_BYTE, data);
free( data ); //free the texture
return texture; //return whether it was successful
}
void display( void )
{
//set view of scene
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluOrtho2D( snake->x - start_x, (640 + snake->x) - start_x, 0.0, 480);
//gluOrtho2D(0, 640, 0, 480);
//draw texture on background
glBindTexture( GL_TEXTURE_2D, texture );
glPushMatrix();
glBegin(GL_QUADS);
glTexCoord2i(0,0); glVertex2f(snake->x - start_x, 480);
glTexCoord2i(1,0); glVertex2f(640 + snake->x, 480);
glTexCoord2i(1,1); glVertex2f(640 + snake->x, 0);
glTexCoord2i(0,1); glVertex2f(snake->x - start_x, 0);
glEnd();
glPopMatrix();
glColor3f( 1.0, 1.0, 1.0 );
//render scene
glutSwapBuffers();
}
int main( int argc, char** argv )
{
glutInit( &argc, argv );
glutInitDisplayMode (GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize (640, 480);
glutInitWindowPosition (100, 100);
glutCreateWindow( "Slidey Snake" );
glutDisplayFunc( display );
//glutKeyboardFunc( buttonmap );
//glutReshapeFunc(reshape);
//init();
//Timer(0);
texture = LoadTexture("sky.png", 256, 256);
glutMainLoop();
return 0;
}
any ideas?
I must admit, I laughed at this one :) You are using the raw PNG file data as being RGB pixel data. That is not correct. PNG files are compressed. You first need to decode them before you feed them into OpenGL. Slick2D is a library that does the job nicely.

How can i use a texture .jpg image for an openGL background window in mac?

I want to set a background for an openGL window for mac. background will take a jpg or png file.
Here is my code..
GLuint texture; //the array for our texture
GLfloat angle = 0.0;
GLuint LoadTexture (const char * filename, int width, int height ){
// GLuint texture;
unsigned char * data;
FILE * file;
//The following code will read in our RAW file
file = fopen( filename, "rb" );
if ( file == NULL ) return 0;
data = (unsigned char *)malloc( width * height * 3 );
fread( data, width * height * 3, 1, file );
fclose( file );
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
// // when texture area is small, bilinear filter the closest mipmap
// glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
// GL_LINEAR_MIPMAP_NEAREST );
// // when texture area is large, bilinear filter the original
// glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
//
// // the texture wraps over at the edges (repeat)
// glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
// glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
//
// //Generate the texture
// glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0,GL_RGB, GL_UNSIGNED_BYTE, data);
// select modulate to mix texture with color for shading
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
// when texture area is small, bilinear filter the closest mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_LINEAR_MIPMAP_NEAREST );
// when texture area is large, bilinear filter the first mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
// // the texture wraps over at the edges (repeat)
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
// build our texture mipmaps
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,
GL_RGB, GL_UNSIGNED_BYTE, data );
free(data);
return texture; //return whether it was successful
}
void FreeTexture( GLuint texture ){
glDeleteTextures( 1, &texture );
}
void cube () {
glEnable(GL_TEXTURE_2D);
glBindTexture( GL_TEXTURE_2D, texture ); //bind the texture
glPushMatrix();
glRotatef( angle, 0.0f, 0.0f, 1.0f );
glBegin( GL_QUADS );
glTexCoord2d(0.0,0.0); glVertex2d(-1.0,-1.0);
glTexCoord2d(1.0,0.0); glVertex2d(+1.0,-1.0);
glTexCoord2d(1.0,1.0); glVertex2d(+1.0,+1.0);
glTexCoord2d(0.0,1.0); glVertex2d(-1.0,+1.0);
glEnd();
glPopMatrix();
glutSwapBuffers();
//glutSolidCube(2);
}
void display () {
glClearColor (0.0,0.0,0.0,1.0);
glClear (GL_COLOR_BUFFER_BIT);
glLoadIdentity();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
texture = LoadTexture( "/Users/macbook/MatrixEngineClientSample/Fighters/Sunset03.jpg", 256, 256 ); //load the texture
glEnable( GL_TEXTURE_2D ); //enable 2D texturing
// glEnable(GL_TEXTURE_GEN_S); //enable texture coordinate generation
// glEnable(GL_TEXTURE_GEN_T);
cube();
FreeTexture( texture );
//glutSwapBuffers();
//angle ++;
}
void reshape (int w, int h) {
glViewport (0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode (GL_PROJECTION);
//glLoadIdentity ();
gluPerspective (50, (GLfloat)w / (GLfloat)h, 1.0, 100.0);
glMatrixMode (GL_MODELVIEW);
}
int main (int argc, char **argv) {
glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow ("A basic OpenGL Window");
glutDisplayFunc (display);
glutIdleFunc (display);
glutReshapeFunc (reshape);
glutMainLoop ();
return 0;
}
EDIT
I want to see this image as a background of the openGL window...image is below..
but it showing this...
I consulted this Apple guide.
The problem is that the file is compressed AND has a header, and with your code you are even using part of the file header as an image source.
I would replace this code:
// GLuint texture;
unsigned char * data;
FILE * file;
//The following code will read in our RAW file
file = fopen( filename, "rb" );
if ( file == NULL ) return 0;
data = (unsigned char *)malloc( width * height * 3 );
fread( data, width * height * 3, 1, file );
fclose( file );
With something more similar to this:
CFURLRef urlRef = (CFURLRef)[NSURL fileURLWithPath:#"/Users/macbook/MatrixEngineClientSample/Fighters/Sunset03.jpg"];
CGImageSourceRef myImageSourceRef = CGImageSourceCreateWithURL(url, NULL);
CGImageRef myImageRef = CGImageSourceCreateImageAtIndex(myImageSourceRef, 0, NULL);
CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(myImageRef));
unsigned char *data = CFDataGetBytePtr(data);
You may need to add Core Graphics and Core Foundation to the list of your linked frameworks.
PNG and JPG images (as with most other image formats) require some form of decompression/decoding, so loading them raw from a file wont produce expected results. It should work with bmp or uncompressed tga images after reading the file header though :/ . Anyway, here are a few image loading libraries that should make loading images easy:
SOIL
DevIL
FreeImage
GLI

OpenGL texture mapping coordinates

I need to be able to stretch the image texture i'm importing over the entire 2d or 3d (face) shape. It will only render in the top right of the shape, and either repeat - if I enable GL_REPEAT, or the image will stretch from the sides projecting to the edge horribly if i enable GL_CLAMP.
Here's my code:
#include "stdafx.h"
#include "glut.h"
#include <stdio.h>
#include <windows.h>
#include <stdlib.h>
GLuint texture;
float xRotation = 0.0f;
void drawScene1 (void) {
//glRotatef(xRotation,0.0f,1.0f,0.0f);
glBindTexture(GL_TEXTURE_2D, texture);
//glutSolidCube(1.0f);
glBegin(GL_POLYGON);
glTexCoord2d(0,1);
glVertex2d(-1.5,-1.5);
glTexCoord2d(1,1);
glVertex2d(1.0,-2.0);
glTexCoord2d(1,0);
glVertex2d(+1.5,+1.5);
glTexCoord2d(0,0);
glVertex2d(-1.5,+1.5);
glEnd();
}
void FreeTexture(GLuint texture) {
glDeleteTextures(1, &texture);
}
GLuint LoadTexture(const char * filename, int width, int height) {
GLuint texture;
unsigned char * data;
FILE * file;
file = fopen(filename, "rb");
if ( file == NULL ) return 0;
data = (unsigned char *)malloc(width * height * 3);
fread(data, width * height * 3, 1, file);
fclose(file);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
//glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
//glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
//glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, width, height, GL_RGB, GL_UNSIGNED_BYTE, data);
free(data);
return texture;
}
void init (void) {
glShadeModel(GL_SMOOTH);
glMatrixMode(GL_PROJECTION);
//glLoadIdentity();
//gluOrtho2D(0,500,0,500);
//glClearDepth(1);
//glEnable (GL_DEPTH_TEST);
//glEnable (GL_LIGHTING);
//glEnable (GL_LIGHT0);
//glEnable(GL_COLOR_MATERIAL);
glEnable(GL_NORMALIZE);
glEnable(GL_TEXTURE_2D);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
}
void display (void) {
glClearColor(0.05,0.05,0.1,1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
texture = LoadTexture("img.raw", 256, 256);
drawScene1();
FreeTexture(texture);
glutSwapBuffers();
xRotation++;
}
int main (int argc, char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(500,500);
glutInitWindowPosition(100,100);
glutCreateWindow("Virgin");
init();
glutDisplayFunc(display);
glutIdleFunc(display);
glutMainLoop();
return 0;
}
Please decide: Implicit texture coordinate generation:
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
or explicit texture coordinate supplications:
glTexCoord(...)
Implicit will override explicit.
void display (void) {
/*... */
texture = LoadTexture("img.raw", 256, 256);
drawScene1();
FreeTexture(texture);
/* ... */
}
Don't load and delete the texture for each rendered frame. Load the textures at startup and only bind them when rendering.
Remove the following lines:
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
You already have texture coordinates entered via glTexCoord2f(), no need to generate them.