glBindTexture(GL_TEXTURE_2D, texture[filter*2]); // This Will Select The BG Texture ( NEW )
glPushMatrix();
glTranslatef(0.0f, 0.0f, –24.0f);
glBegin(GL_QUADS);
glNormal3f( 0.0f, 0.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-13.3f, –10.0f, 10.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 13.3f, –10.0f, 10.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 13.3f, 10.0f, 10.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-13.3f, 10.0f, 10.0f);
glEnd();
glPopMatrix();
xrot+=xspeed;
yrot+=yspeed;
return TRUE; // Keep Going
}
The last thing we have to do is update the spacebar section of code to reflect (No Pun Intended) the changes we made to the Quadratic objects being rendered. (We removed the discs)
if (keys[' '] && !sp) {
sp=TRUE;
object++;
if (object>3) object=0;
}
We're done! Now you can do some really impressive things with Environment mapping like making an almost accurate reflection of a room! I was planning on showing how to do Cube Environment Mapping in this tutorial too but my current video card does not support cube mapping. Maybe in a month or so after I buy a GeForce 2 :) Also I taught myself environment mapping (mostly because I couldnt find too much information on it) so if anything in this tutorial is inaccurate, Email Me or let NeHe know.
Thanks, and Good Luck!
Visit my site: http://www.tiptup.com/
* DOWNLOAD Visual C++ Code For This Lesson.
* DOWNLOAD Mac OS X/Cocoa Code For This Lesson. (Conversion by Bryan Blackburn)
Lesson 24
This tutorial is far from visually stunning, but you will definitely learn a few new things by reading through it. I have had quite a few people ask me about extensions, and how to find out what extensions are supported on a particular brand of video card. This tutorial will teach you how to find out what OpenGL extensions are supported on any type of 3D video card.
I will also teach you how to scroll a portion of the screen without affecting any of the graphics around it using scissor testing. You will also learn how to draw line strips, and most importantly, in this tutorial we will drop the AUX library completely, along with Bitmap images. I will show you how to use Targa (TGA) images as textures. Not only are Targa files easy to work with and create, they support the ALPHA channel, which will allow you to create some pretty cool effects in future projects!
The first thing you should notice in the code below is that we no longer include the glaux header file (glaux.h). It is also important to note that the glaux.lib file can also be left out! We're not working with bitmaps anymore, so there's no need to include either of these files in our project.
Also, using glaux, I always received one warning message. Without glaux there should be zero errors, zero warnings.
#include <windows.h> // Header File For Windows
#include <stdio.h> // Header File For Standard Input / Output
#include <stdarg.h> // Header File For Variable Argument Routines
#include <string.h> // Header File For String Management
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
HDC hDC=NULL; // Private GDI Device Context
HGLRC hRC=NULL; // Permanent Rendering Context
HWND hWnd=NULL; // Holds Our Window Handle
HINSTANCE hInstance; // Holds The Instance Of The Application
bool keys[256]; // Array Used For The Keyboard Routine
bool active=TRUE; // Window Active Flag Set To TRUE By Default
bool fullscreen=TRUE; // Fullscreen Flag Set To Fullscreen Mode By Default
The first thing we need to do is add some variables. The first variable scroll will be used to scroll a portion of the screen up and down. The second variable maxtokens will be used to keep track of how many tokens (extensions) are supported by the video card.
base is used to hold the font display list.
swidth and sheight are used to grab the current window size. We use these two variable to help us calculate the scissor coordinates later in the code.
int scroll; // Used For Scrolling The Screen
int maxtokens; // Keeps Track Of The Number Of Extensions Supported
int swidth; // Scissor Width
int sheight; // Scissor Height
GLuint base; // Base Display List For The Font
Now we create a structure to hold the TGA information once we load it in. The first variable imageData will hold a pointer to the data that makes up the image. bpp will hold the bits per pixel used in the TGA file (this value should be 24 or 32 bits depending on whether or not there is an alpha channel). The third variable width will hold the width of the TGA image. height will hold the height of the image, and texID will be used to keep track of the textures once they are built. The structure will be called TextureImage.
The line just after the structure (TextureImage textures[1]) sets aside storage for the one texture that we will be using in this program.
typedef struct // Create A Structure
{
GLubyte *imageData; // Image Data (Up To 32 Bits)
GLuint bpp; // Image Color Depth In Bits Per Pixel
GLuint width; // Image Width
GLuint height; // Image Height
GLuint texID; // Texture ID Used To Select A Texture
} TextureImage; // Structure Name
TextureImage textures[1]; // Storage For One Texture
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration For WndProc
Now for the fun stuff! This section of code will load in a TGA file and convert it into a texture for use in the program. One thing to note is that this code will only load 24 or 32 bit uncompressed TGA files. I had a hard enough time making the code work with both 24 and 32 bit TGA's :) I never said I was a genious. I'd like to point out that I did not write all of this code on my own. Alot of the really good ideas I got from reading through random sites on the net. I just took all the good ideas and combined them into code that works well with OpenGL. Not easy, not extremely difficult!
We pass two parameters to this section of code. The first parameter points to memory that we can store the texture in (*texture). The second parameter is the name of the file that we want to load (*filename).
The first variable TGAheader[ ] holds 12 bytes. We'll compare these bytes with the first 12 bytes we read from the TGA file to make sure that the file is indeed a Targa file, and not some other type of image.
TGAcompare will be used to hold the first 12 bytes we read in from the TGA file. The bytes in TGAcompare will then be compared with the bytes in TGAheader to make sure everything matches.