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nick2price

OpenGL display window black, no skymap

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nick2price    120
I followed a tutorial to create a skymap. The problem was that the tutorial used glaux and created the window not through a main, so i had to change these couple of things. Everything compiles now but for some reason the display screen is just black. Can someone look at the code to see if there is a logical reason for this. Thanks very much skybox.cpp
#include "stdafx.h"
#include <GL/glut.h>
#include <windows.h>
#include <stdio.h>  //for file access							
#include <gl\gl.h>													
#include "skybox.h"
#include "glbmp.h"


GLuint skybox::LoadTexture(const char * bitmap_file)
{
   GLuint texture = 0; //OpenGL texture to create and return
   glbmp_t bitmap;     //object to fill with data from glbmp
 
   
   if(!glbmp_LoadBitmap(bitmap_file, 0, &bitmap))
   {
      fprintf(stderr, "Error loading bitmap file: %s\n", bitmap_file);
   }
 
   //generate and bind the OpenGL texture
   glGenTextures(1, &texture);
   glBindTexture(GL_TEXTURE_2D, texture);
 
   //copy data from bitmap into texture
   glTexImage2D(GL_TEXTURE_2D, 0, 3, bitmap.width, bitmap.height,
                0, GL_RGB, GL_UNSIGNED_BYTE, bitmap.rgb_data);
 
   //set up texture filtering
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
   //free the bitmap
   glbmp_FreeBitmap(&bitmap);
 
   return texture;
}
 


void skybox::Init() {

	OFFSET = 1/512.0; //set offset value for skybox

	rot_x = 0.0; rot_y = 0.0;

    GLuint tex1;
	GLuint tex2;
	GLuint tex3;
	GLuint tex4;
	GLuint tex5;
	GLuint tex6;

	tex1 = LoadTexture("images/left1.bmp");
	tex2 = LoadTexture("images/front1.bmp");
	tex3 = LoadTexture("images/right1.bmp");
	tex4 = LoadTexture("images/back1.bmp");
	tex5 = LoadTexture("images/down1.bmp");
	tex6 = LoadTexture("images/up1.bmp");

}


//This is where the magic happens
void skybox::draw() {

		glPushMatrix();
	glRotated(rot_x, 1.0, 0.0, 0.0);	//Rotate around the x axis
	glRotated(rot_y, 0.0, 1.0, 0.0);	//Rotate around the y axis

	glColor3f(1.0f,1.0f,1.0f);			//Set colour to White
	glEnable(GL_TEXTURE_2D);			//Enable texture mapping
	glDisable (GL_DEPTH_TEST);			//Disable depth testing

		//before you can use a texture you have to bind it
		glBindTexture(GL_TEXTURE_2D, texture[0 + text_offset]);

		glBegin (GL_QUADS);	
		
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,0.0 + OFFSET);	glVertex3d (-10.0,-10.0,10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,0.0 + OFFSET);	glVertex3d (-10.0,-10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,1.0 - OFFSET);	glVertex3d (-10.0,10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,1.0 - OFFSET);	glVertex3d (-10.0,10.0,10.0);

		glEnd ();				

		glBindTexture(GL_TEXTURE_2D, texture[1 + text_offset]);
		glBegin (GL_QUADS);
		
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,0.0 + OFFSET);	glVertex3d (-10.0,-10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,0.0 + OFFSET);	glVertex3d (10.0,-10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,1.0 - OFFSET);	glVertex3d (10.0,10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,1.0 - OFFSET);	glVertex3d (-10.0,10.0,-10.0);
		glEnd ();

		glBindTexture(GL_TEXTURE_2D, texture[2 + text_offset]);
		glBegin (GL_QUADS);
		
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);
				glNormal3d (0.0,0.0,10.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,-10.0);

		glEnd ();

		glBindTexture(GL_TEXTURE_2D, texture[3 + text_offset]);	
		glBegin (GL_QUADS);
			
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,-10.0,10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,10.0,10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);
		
		glEnd ();

		glBindTexture(GL_TEXTURE_2D, texture[4 + text_offset]);	
		glBegin (GL_QUADS);
			
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,-10.0,10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,-10.0,-10.0);
			glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,-10.0,-10.0);
		
		glEnd ();

		glBindTexture(GL_TEXTURE_2D, texture[5 + text_offset]);
		glBegin (GL_QUADS);
		
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,10.0,-10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);
				glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,10.0,10.0);
				
		glEnd ();

	//Re-Enable the depth test
	glEnable(GL_DEPTH_TEST);
	//disable texture mapping
	glDisable(GL_TEXTURE_2D);
	glPopMatrix();
	

}

skybox.h
#define MAX_TEXTURES 24

class skybox {
public:  //just make everything public than you don't have to worry about access

	skybox() { } //constructor

	GLuint LoadTexture(const char * bitmap_file);
	void Init();
	void draw();


	GLuint	texture[MAX_TEXTURES];

	//used to correct the edges of the skybox overlap
	//try setting this to 0.0 in the Init() and you will see the seams of the textures
	double	OFFSET,	rot_x, rot_y;
	long	text_offset;
};
main.cpp
#include "stdafx.h"
#include <GL/glut.h>
#include <windows.h>
#include <stdio.h>  //for file access							
#include <gl\gl.h>													
#include "skybox.h"
#include "glbmp.h"

int screen_width=800;
int screen_height=600;

skybox		aSkyBox;

GLvoid ReSizeGLScene(GLsizei width, GLsizei height) {

	if (height<=0) { height=1; }

	glViewport(0,0,width,height);

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

int InitGL(GLvoid) {
	
	glEnable(GL_TEXTURE_2D);
	glShadeModel(GL_SMOOTH);							//Try GL_FLAT to see the difference
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);				//Background colour
	glClearDepth(1.0f);
	glEnable(GL_DEPTH_TEST);							//Enables depth testing
	glDepthFunc(GL_LEQUAL);								//Specifies how Depth testing is done
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	//Affects quality of colour and texture interpolation
	glFrontFace (GL_CCW);								//Specifies that the front of a face is defined 
														//in a Counter Clockwise manner
	glCullFace(GL_BACK);								//Specifies that the back of faces are not shown
														//so OpenGL does not need to draw things twice
	glEnable(GL_CULL_FACE);								//Enables culling of faces


	aSkyBox.Init();			//Initalize the Skybox


	return TRUE;
}

void DrawGLScene(GLvoid) {

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();

	aSkyBox.draw();
	glutSwapBuffers(); 
 
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);    
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(screen_width,screen_height);
    glutInitWindowPosition(0,0);
    glutCreateWindow("Coursework 2");    
 
	glutDisplayFunc(DrawGLScene);
    glutMainLoop();

    return(0);    
}
thank you

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Aurvandil    101
Perhaps I just missed it but where are you filling out the "texture[MAX_TEXTURES];" array with the textures generated in skybox.Init()? If this array isn't getting filled you are passing "junk" data into every call to glBindTexture. (Depends on your compiler as to what the default for int is)

Try filling out the array with tex1, tex2...etc from the Init function.

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nick2price    120
kk, see i missed that, cheers. I have changed my code to this

#include "stdafx.h"
#include <GL/glut.h>
#include <windows.h>
#include <stdio.h> //for file access
#include <gl\gl.h>
#include "skybox.h"
#include "glbmp.h"


bool skybox::LoadTexture(unsigned int & aTexture, const char * bitmap_file)
{
GLuint texture = 0; //OpenGL texture to create and return
glbmp_t bitmap; //object to fill with data from glbmp


if(!glbmp_LoadBitmap(bitmap_file, 0, &bitmap))
{
fprintf(stderr, "Error loading bitmap file: %s\n", bitmap_file);
}

//generate and bind the OpenGL texture
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);

//copy data from bitmap into texture
glTexImage2D(GL_TEXTURE_2D, 0, 3, bitmap.width, bitmap.height,
0, GL_RGB, GL_UNSIGNED_BYTE, bitmap.rgb_data);

//set up texture filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

//free the bitmap
glbmp_FreeBitmap(&bitmap);

return true;
}



void skybox::Init() {

OFFSET = 1/512.0; //set offset value for skybox

rot_x = 0.0; rot_y = 0.0;



LoadTexture(texture[0], "images/left1.bmp");
LoadTexture(texture[1], "images/front1.bmp");
LoadTexture(texture[2], "images/right1.bmp");
LoadTexture(texture[3], "images/back1.bmp");
LoadTexture(texture[4], "images/down1.bmp");
LoadTexture(texture[5], "images/up1.bmp");

}


//This is where the magic happens
void skybox::draw() {

glPushMatrix();
glRotated(rot_x, 1.0, 0.0, 0.0); //Rotate around the x axis
glRotated(rot_y, 0.0, 1.0, 0.0); //Rotate around the y axis

glColor3f(1.0f,1.0f,1.0f); //Set colour to White
glEnable(GL_TEXTURE_2D); //Enable texture mapping
glDisable (GL_DEPTH_TEST); //Disable depth testing

//before you can use a texture you have to bind it
glBindTexture(GL_TEXTURE_2D, texture[0 + text_offset]);

glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,0.0 + OFFSET); glVertex3d (-10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,0.0 + OFFSET); glVertex3d (-10.0,-10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,1.0 - OFFSET); glVertex3d (-10.0,10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,1.0 - OFFSET); glVertex3d (-10.0,10.0,10.0);

glEnd ();

glBindTexture(GL_TEXTURE_2D, texture[1 + text_offset]);
glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,0.0 + OFFSET); glVertex3d (-10.0,-10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,0.0 + OFFSET); glVertex3d (10.0,-10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET,1.0 - OFFSET); glVertex3d (10.0,10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET,1.0 - OFFSET); glVertex3d (-10.0,10.0,-10.0);
glEnd ();

glBindTexture(GL_TEXTURE_2D, texture[2 + text_offset]);
glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);
glNormal3d (0.0,0.0,10.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,-10.0);

glEnd ();

glBindTexture(GL_TEXTURE_2D, texture[3 + text_offset]);
glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);

glEnd ();

glBindTexture(GL_TEXTURE_2D, texture[4 + text_offset]);
glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,-10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,-10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,-10.0,-10.0);

glEnd ();

glBindTexture(GL_TEXTURE_2D, texture[5 + text_offset]);
glBegin (GL_QUADS);

glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,0.0 + OFFSET); glVertex3d (-10.0,10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,0.0 + OFFSET); glVertex3d (10.0,10.0,-10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (1.0 - OFFSET ,1.0 - OFFSET); glVertex3d (10.0,10.0,10.0);
glNormal3d (0.0,0.0,1.0); glTexCoord2d (0.0 + OFFSET ,1.0 - OFFSET); glVertex3d (-10.0,10.0,10.0);

glEnd ();

//Re-Enable the depth test
glEnable(GL_DEPTH_TEST);
//disable texture mapping
glDisable(GL_TEXTURE_2D);
glPopMatrix();


}




but for some odd reason, still black. Do you see what could be causing this?

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nick2price    120
I am trying to follow this

bool skybox::Load_Texture(unsigned int & aTexture, char * fileName) {

if(!fileName) return false; //if no file name is given return

FILE *aFile = NULL;
AUX_RGBImageRec *image_record = NULL;

if((aFile = fopen(fileName, "rb")) == NULL) return false;

image_record = auxDIBImageLoadA(fileName); //Function to load BMP

if(!image_record) return false; //check that BMP loaded

glGenTextures(1, &aTexture); //generates 1 texture name

glPixelStorei (GL_UNPACK_ALIGNMENT, 1); //sets how the pixels of the texture are stored

glBindTexture(GL_TEXTURE_2D, aTexture); //binds the name to the target


//build prefiltered textures at different resolutions
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, image_record->sizeX,
image_record->sizeY, GL_RGB, GL_UNSIGNED_BYTE, image_record->data);

//give the texture its attributes
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

// Now we need to free the image data that we loaded since openGL stored it as a texture
if (image_record) { //if we stored data then free the memory
if (image_record->data) { //check if there is any data
free(image_record->data); //free the memory
}
free(image_record); //free the image record
}

return true; //everything should have worked so return true
}


But this is hard to follow as it is using the glaux library which i can no longer use. As a replacemet, i am using this code which is really long and complicated. Is there anything simular i can use which is simular to the above code?

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