i’m learning how to apply texture in openGL. i applyed a texture to one face of a cube and colored the other faces with primitive colors.
before i apply the texture the colors looked fine, and after i apply it they become darker.
what’s wrong?
Disable texturing after drawing first face, otherwise the other faces will get color from texture too.
i did disable it after the first face using glDisable(GL_TEXTURE_2D) but nohting changed
#include <SFML/Graphics.hpp>
#include <cstdio>
GLuint texture[1];
/* Image type - contains height, width, and data */
struct Image {
unsigned long sizeX;
unsigned long sizeY;
char *data;
};
typedef struct Image Image;
// quick and dirty bitmap loader…for 24 bit bitmaps with 1 plane only.
// See http://www.dcs.ed.ac.uk/~mxr/gfx/2d/BMP.txt for more info.
int ImageLoad(const char *filename, Image *image) {
FILE *file;
unsigned long size; // size of the image in bytes.
unsigned long i; // standard counter.
unsigned short int planes; // number of planes in image (must be 1)
unsigned short int bpp; // number of bits per pixel (must be 24)
char temp; // temporary color storage for bgr-rgb conversion.
// make sure the file is there.
if ((file = fopen(filename, "rb"))==NULL)
{
printf("File Not Found : %s
",filename);
return 0;
}
// seek through the bmp header, up to the width/height:
fseek(file, 18, SEEK_CUR);
// read the width
if ((i = fread(&image->sizeX, 4, 1, file)) != 1) {
printf("Error reading width from %s.
", filename);
return 0;
}
printf("Width of %s: %lu
", filename, image->sizeX);
// read the height
if ((i = fread(&image->sizeY, 4, 1, file)) != 1) {
printf("Error reading height from %s.
", filename);
return 0;
}
printf("Height of %s: %lu
", filename, image->sizeY);
// calculate the size (assuming 24 bits or 3 bytes per pixel).
size = image->sizeX * image->sizeY * 3;
// read the planes
if ((fread(&planes, 2, 1, file)) != 1) {
printf("Error reading planes from %s.
", filename);
return 0;
}
if (planes != 1) {
printf("Planes from %s is not 1: %u
", filename, planes);
return 0;
}
// read the bpp
if ((i = fread(&bpp, 2, 1, file)) != 1) {
printf("Error reading bpp from %s.
", filename);
return 0;
}
if (bpp != 24) {
printf("Bpp from %s is not 24: %u
", filename, bpp);
return 0;
}
// seek past the rest of the bitmap header.
fseek(file, 24, SEEK_CUR);
// read the data.
image->data = (char *) malloc(size);
if (image->data == NULL) {
printf("Error allocating memory for color-corrected image data");
return 0;
}
if ((i = fread(image->data, size, 1, file)) != 1) {
printf("Error reading image data from %s.
", filename);
return 0;
}
for (i=0;i<size;i+=3) { // reverse all of the colors. (bgr -> rgb)
temp = image->data[i];
image->data[i] = image->data[i+2];
image->data[i+2] = temp;
}
// we're done.
return 1;
}
// Load Bitmaps And Convert To Textures
void LoadGLTextures() {
// Load Texture
Image *image1;
// allocate space for texture
image1 = (Image *) malloc(sizeof(Image));
if (image1 == NULL) {
printf(“Error allocating space for image”);
exit(0);
}
if (!ImageLoad("dd.bmp", image1)) {
exit(1);
}
// Create Texture
glGenTextures(1, &texture[0]);
glBindTexture(GL_TEXTURE_2D, texture[0]); // 2d texture (x and y size)
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); // scale linearly when image bigger than texture
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); // scale linearly when image smalled than texture
// 2d texture, level of detail 0 (normal), 3 components (red, green, blue), x size from image, y size from image,
// border 0 (normal), rgb color data, unsigned byte data, and finally the data itself.
glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->sizeX, image1->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);
};
int main()
{
sf::Window App(sf::VideoMode(600, 600, 32), “SFML OpenGL”, sf::Style::Close);
glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
glDepthFunc(GL_LEQUAL);
glEnable(GL_TEXTURE_2D);
glShadeModel(GL_SMOOTH);
LoadGLTextures();
glBindTexture(GL_TEXTURE_2D, texture[0]);
while (App.IsOpened())
{
App.SetActive();
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
//back
glColor3f(0.0f,0.0f,0.0f); //cyan
glTexCoord2f(0.0f, 1.0f); glVertex3f(-0.2f,0.2f,0.2f); //top left
glTexCoord2f(1.0f, 1.0f); glVertex3f(0.2f,0.2f,0.2f); //top right
glTexCoord2f(1.0f, 0.0f); glVertex3f(0.2f,-0.2f,0.2f); //bottom right
glTexCoord2f(0.0f, 0.0f); glVertex3f(-0.2f,-0.2f,0.2f); //bottom left
glDisable(GL_TEXTURE_2D);
//bottom
glColor3f(0.0f,1.0f,0.0f); //green
glVertex3f(0.2f,-0.2f,0.2f); //back right
glVertex3f(-0.2f,-0.2f,0.2f); //back left
glVertex3f(-0.2f,-0.2f,-0.2f); //front left
glVertex3f(0.2f,-0.2f,-0.2f); //front right
//front
glColor3f(0.0f,0.0f,1.0f); //blue
glVertex3f(0.2f,-0.2f,-0.2f); //bottom right
glVertex3f(-0.2f,-0.2f,-0.2f); //bottom left
glVertex3f(-0.2f,0.2f,-0.2f); //top left
glVertex3f(0.2f,0.2f,-0.2f); //top right
//top
glColor3f(1.0f,1.0f,0.0f); //yellow
glVertex3f(0.2f,0.2f,-0.2f); //front right
glVertex3f(-0.2f,0.2f,-0.2f); //front left
glVertex3f(-0.2f,0.2f,0.2f); //back left
glVertex3f(0.2f,0.2f,0.2f); //back right
//left
glColor3f(0.0f,1.0f,1.0f); //pink
glVertex3f(-0.2f,-0.2f,-0.2f); //bottom front
glVertex3f(-0.2f,-0.2f,0.2f); //bottom back
glVertex3f(-0.2f,0.2f,0.2f); //top back
glVertex3f(-0.2f,0.2f,-0.2f); //top front
//right
glColor3f(1.0f,0.0f,0.0f); //red
glVertex3f(0.2f,-0.2f,-0.2f); //bottom front
glVertex3f(0.2f,-0.2f,0.2f); //bottom back
glVertex3f(0.2f,0.2f,0.2f); //top back
glVertex3f(0.2f,0.2f,-0.2f); //top front
glEnd();
glFlush();
App.Display();
sf::Event Event;
while (App.GetEvent(Event))
{
if (Event.Type == sf::Event::Closed)
App.Close();
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Escape))
App.Close();
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Right))
glRotated(20.0d,0.0d,0.2d,0.0d);
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Left))
glRotated(-20.0d,0.0d,0.2d,0.0d);
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Up))
glRotated(20.0d,0.2d,0.0d,0.0d);
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Down))
glRotated(-20.0d,0.2d,0.0d,0.0d);
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::PageUp))
glRotated(20.0d,0.0d,0.0d,0.2d);
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::PageDown))
glRotated(-20.0d,0.0d,0.0d,0.2d);
}
}
return EXIT_SUCCESS;
}
Long code for other people is hard enough to read, so please at least use the [ code ] my long code here[ /code ] (without the spaces) tags …
Never use glDisable between glBegin and glEnd functions.
http://www.opengl.org/sdk/docs/man/xhtml/glBegin.xml
Also,
glColor3f(0.0f,0.0f,0.0f); //cyan
This is not cyan, this is black. This is why your textured face could look dark.
you are absolutely right, thanks arts 
this is the correct code now :
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glBegin(GL_QUADS);
//back
glColor3f(1.0f,1.0f,1.0f); //white
glTexCoord2f(0.0f, 1.0f); glVertex3f(-0.2f,0.2f,0.2f); //top left
glTexCoord2f(1.0f, 1.0f); glVertex3f(0.2f,0.2f,0.2f); //top right
glTexCoord2f(1.0f, 0.0f); glVertex3f(0.2f,-0.2f,0.2f); //bottom right
glTexCoord2f(0.0f, 0.0f); glVertex3f(-0.2f,-0.2f,0.2f); //bottom left
glEnd();
glDisable(GL_TEXTURE_2D);
glBegin(GL_QUADS);
//bottom
glColor3f(0.0f,1.0f,0.0f); //green
glVertex3f(0.2f,-0.2f,0.2f); //back right
glVertex3f(-0.2f,-0.2f,0.2f); //back left
glVertex3f(-0.2f,-0.2f,-0.2f); //front left
glVertex3f(0.2f,-0.2f,-0.2f); //front right
//front
glColor3f(0.0f,0.0f,1.0f); //blue
glVertex3f(0.2f,-0.2f,-0.2f); //bottom right
glVertex3f(-0.2f,-0.2f,-0.2f); //bottom left
glVertex3f(-0.2f,0.2f,-0.2f); //top left
glVertex3f(0.2f,0.2f,-0.2f); //top right
//top
glColor3f(1.0f,1.0f,0.0f); //yellow
glVertex3f(0.2f,0.2f,-0.2f); //front right
glVertex3f(-0.2f,0.2f,-0.2f); //front left
glVertex3f(-0.2f,0.2f,0.2f); //back left
glVertex3f(0.2f,0.2f,0.2f); //back right
//left
glColor3f(0.0f,1.0f,1.0f); //pink
glVertex3f(-0.2f,-0.2f,-0.2f); //bottom front
glVertex3f(-0.2f,-0.2f,0.2f); //bottom back
glVertex3f(-0.2f,0.2f,0.2f); //top back
glVertex3f(-0.2f,0.2f,-0.2f); //top front
//right
glColor3f(1.0f,0.0f,0.0f); //red
glVertex3f(0.2f,-0.2f,-0.2f); //bottom front
glVertex3f(0.2f,-0.2f,0.2f); //bottom back
glVertex3f(0.2f,0.2f,0.2f); //top back
glVertex3f(0.2f,0.2f,-0.2f); //top front
glEnd();