Texture Mapping

glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);

#include <algorithm>#include <vector>#include <GL/glut.h>//	an id we use to identify our textureGLuint textureID;class Random{	public:		unsigned char operator()() const		{			//	just generate a random number from zero to two hundred and fifty-five			return (std::rand() * 255) / RAND_MAX;		}};void createTexture(){	//	tell OpenGL that we're creating a new texture and get a new id for it.	glGenTextures(1, &textureID);	//	create a 16 × 16 block of random RGB values	std::vector<unsigned char> textureData(16 * 16 * 3);	std::generate(textureData.begin(), textureData.end(), Random());	//	tell OpenGL which texture we're operating on	glBindTexture(GL_TEXTURE_2D, textureID);	//	tell OpenGL that we want this texture to be linearly filtered	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);	// create the texture	//		this is level 0 (the main version of the texture)	//		we only care that OpenGL stores red, green and blue values internally, so the internalformat is set as GL_RGB	//		the texture is 16 pixels wide	//		the texture is 16 pixels high	//		we don't want a border round the texture	//		the data we're giving OpenGL is in RGB format	//		the data we're giving OpenGL is made up of unsigned bytes	//		&textureData[0] is a pointer to our data	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 16, 16, 0, GL_RGB, GL_UNSIGNED_BYTE, &textureData[0]);	// tell OpenGL to use texturing whenever it draws anything	glEnable(GL_TEXTURE_2D);}void reshape(int width, int height){	//	set up the projection matrix and viewport	glMatrixMode(GL_PROJECTION);	glLoadIdentity();	glViewport(0, 0, width, height);	glOrtho(-256, 256, 256, -256, -1, 1);	//	reset the modelview matrix	glMatrixMode(GL_MODELVIEW);	glLoadIdentity();}void display(){	//	clear the buffers	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	//	draw a quad	glBegin(GL_QUADS);		//	set a texture coordinate (top left)		glTexCoord2f(0, 0);		//	draw a vertex.  This uses the last set texture coordinate		glVertex2f(-100, -100);		//	set a texture coordinate (top right)		glTexCoord2f(1, 0);		//	draw a vertex.  This uses the last set texture coordinate		glVertex2f(100, -100);		//	set a texture coordinate (bottom right)		glTexCoord2f(1, 1);		//	draw a vertex.  This uses the last set texture coordinate		glVertex2f(100, 100);		//	set a texture coordinate (bottom left)		glTexCoord2f(0, 1);		//	draw a vertex.  This uses the last set texture coordinate		glVertex2f(-100, 100);	glEnd();	//	swap the buffers so we can actually see it	glutSwapBuffers();}int main(int argc, char** argv){	//	initialise GLUT	glutInit(&argc, argv);	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);	glutInitWindowPosition(0, 0);	glutInitWindowSize(512, 512);	glutCreateWindow("Minimal Textures");	glutReshapeFunc(reshape);	glutDisplayFunc(display);	//	create the texture	createTexture();	//	set the darn thing going	glutMainLoop();	return 0;}