Heighmap

#define MAP_X		32
#define MAP_Z		32	

unsigned char *LoadBitmapFile(char *filename, BITMAPINFOHEADER *bitmapInfoHeader)
{
	FILE *filePtr;
	BITMAPFILEHEADER	bitmapFileHeader;
	unsigned char		*bitmapImage;
	int					imageIdx = 0;
	unsigned char		tempRGB;

	filePtr = fopen(filename, "rb");
	if (filePtr == NULL)
		return NULL;

	fread(&bitmapFileHeader, sizeof(BITMAPFILEHEADER), 1, filePtr);
	
	if (bitmapFileHeader.bfType != BITMAP_ID)
	{
		fclose(filePtr);
		return NULL;
	}

	fread(bitmapInfoHeader, sizeof(BITMAPINFOHEADER), 1, filePtr);
	fseek(filePtr, bitmapFileHeader.bfOffBits, SEEK_SET);
	bitmapImage = (unsigned char*)malloc(bitmapInfoHeader->biSizeImage);
	if (!bitmapImage)
	{
		free(bitmapImage);
		fclose(filePtr);
		return NULL;
	}

	fread(bitmapImage, 1, bitmapInfoHeader->biSizeImage, filePtr);
	if (bitmapImage == NULL)
	{
		fclose(filePtr);
		return NULL;
	}

	for (imageIdx = 0; imageIdx < bitmapInfoHeader->biSizeImage; imageIdx+=3)
	{
		tempRGB = bitmapImage[imageIdx];
		bitmapImage[imageIdx] = bitmapImage[imageIdx + 2];
		bitmapImage[imageIdx + 2] = tempRGB;
	}

	fclose(filePtr);
	return bitmapImage;
}

...

void InitializeTerrain()
{
	for (int z = 0; z < MAP_Z; z++)
	{
		for (int x = 0; x < MAP_X; x++)
		{
			terrain[x][z][0] = float(x)*MAP_SCALE;				
			terrain[x][z][1] = (float)imageData[(z*MAP_Z+x)*3];
			terrain[x][z][2] = -float(z)*MAP_SCALE;
		}
	}
}
		

...


void render()
...
	imageData = LoadBitmapFile("terrain2.bmp", &bitmapInfoHeader);
	InitializeTerrain();
...


	glBindTexture(GL_TEXTURE_2D, land);
	for (int z = 0; z < MAP_Z-1; z++)
	{
		glBegin(GL_TRIANGLE_STRIP);
		for (int x = 0; x < MAP_X-1; x++)
		{
			// for each vertex, we calculate the grayscale shade color, 
			// we set the texture coordinate, and we draw the vertex.
			/*
			   the vertices are drawn in this order:

			   0  ---> 1
			          /
				    /
			     |/
			   2  ---> 3
			*/
		
			// draw vertex 0
			glColor3f(terrain[x][z][1]/255.0f, terrain[x][z][1]/255.0f, terrain[x][z][1]/255.0f);
			glTexCoord2f(0.0f, 0.0f);
			glVertex3f(terrain[x][z][0], terrain[x][z][1], terrain[x][z][2]);

			// draw vertex 1
			glTexCoord2f(1.0f, 0.0f);
			glColor3f(terrain[x+1][z][1]/255.0f, terrain[x+1][z][1]/255.0f, terrain[x+1][z][1]/255.0f);
			glVertex3f(terrain[x+1][z][0], terrain[x+1][z][1], terrain[x+1][z][2]);

			// draw vertex 2
			glTexCoord2f(0.0f, 1.0f);
			glColor3f(terrain[x][z+1][1]/255.0f, terrain[x][z+1][1]/255.0f, terrain[x][z+1][1]/255.0f);
			glVertex3f(terrain[x][z+1][0], terrain[x][z+1][1], terrain[x][z+1][2]);

			// draw vertex 3
			glColor3f(terrain[x+1][z+1][1]/255.0f, terrain[x+1][z+1][1]/255.0f, terrain[x+1][z+1][1]/255.0f);
			glTexCoord2f(1.0f, 1.0f);
			glVertex3f(terrain[x+1][z+1][0], terrain[x+1][z+1][1], terrain[x+1][z+1][2]);
		}
		glEnd();
	}
....
}