rendering bmp not appearing - c++

Question

i can't seem to load a bitmap and display it :S ... does anyone know what is wrong here? my bmp is 256 x 265 in size. I currently can only see a black screen (nothing is being shown). Any help would be appreciated!
int DrawGLScene(GLvoid) // Here's Where We Do All The Drawing
{
GLuint texture = LoadBMP("C:/Untitled.bmp");
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glBegin(GL_QUADS);
glTexCoord2d(2.8f, 2.8f); glVertex2f(2.8f, 2.8f);
glTexCoord2d(2.8f, 2.8f); glVertex2f(2.8f, 2.8f);
glTexCoord2d(2.8f, 2.8f); glVertex2f(2.8f, 2.8f);
glTexCoord2d(2.8f, 2.8f); glVertex2f(2.8f, 2.8f);
glEnd();
glDisable(GL_TEXTURE_2D);
return TRUE; // Keep Going
}
GLuint LoadBMP(const char *fileName)
{
FILE *file;
unsigned char header[54];
unsigned int dataPos;
unsigned int size;
unsigned int width, height;
unsigned char *data;
file = fopen(fileName, "rb");
if (file == NULL)
{
MessageBox(NULL, L"Error: Invaild file path!", L"Error", MB_OK);
return false;
}
if (fread(header, 1, 54, file) != 54)
{
MessageBox(NULL, L"Error: Invaild file!", L"Error", MB_OK);
return false;
}
if (header[0] != 'B' || header[1] != 'M')
{
MessageBox(NULL, L"Error: Invaild file!", L"Error", MB_OK);
return false;
}
dataPos = (int)&(header[0x0A]);
size = (int)&(header[0x22]);
width = (int)&(header[0x12]);
height = (int)&(header[0x16]);
if (size == NULL)
size = width * height * 3;
if (dataPos == NULL)
dataPos = 54;
data = new unsigned char[size];
fread(data, 1, size, file);
fclose(file);
GLuint texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
return texture;
}

Answer 1

Of course you do not see anything, you are using the same texture coordinate for every vertex :)
Texture coordinates in OpenGL (unless you are using something like a special rectangle texture) are normalized in the range 0.0 - 1.0. Where (0.0, 0.0) represents the bottom-left corner of the image and (1.0, 1.0) represents the top-right. You should consider stretching the image over your quad exactly one time, so use a combination of all four corners for your coordinates.
Also, use glTexCoord2f (...) since you are clearly using single-precision floating-point coordinates and not double-precision.
Consider this instead:
glBegin( GL_QUADS);
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);
glTexCoord2f (1.0f, 0.0f); glVertex2f ( 1.0f, -1.0f);
glEnd ();
This code addresses two issues:
It will stretch your bitmap over the quad exactly one time
The vertex coordinates will cover your entire viewport