void gluPerspective_( GLdouble fovY, GLdouble aspect, GLdouble zNear, GLdouble zFar ) {	const GLdouble pi = 3.1415926535897932384626433832795;	GLdouble fH = tan( fovY / 360 * pi ) * zNear;	GLdouble fW = fH * aspect;	glFrustum( -fW, fW, -fH, fH, zNear, zFar );}/* Draw scene objects */void renderGL() {	static float theta = 0.0f;	theta += delta;	// Clear and reset	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Render all map tiles (24x24)	glLoadIdentity();	glRotatef(theta, 1.0f, 0.0f, 0.0f);	glBindTexture(GL_TEXTURE_2D, textures[0]); // Tilemap texture (48x(48*n))	glBegin(GL_QUADS);				for (int x = -12; x < 12; x++) {			for (int y = -12; y < 12; y++) {				GLfloat tex = ((float)(rand() % 20)) / 20.0f; // Random tile				const GLfloat td = 1.0f / 20.0f;				glTexCoord2f(0.0f, tex+td);				glVertex3f(x / 12.0f, y / 12.0f, 0.0f);				glTexCoord2f(1.0f, tex+td);				glVertex3f((x+1) / 12.0f, y / 12.0f, 0.0f);				glTexCoord2f(1.0f, tex);				glVertex3f((x+1) / 12.0f, (y+1) / 12.0f, 0.0f);				glTexCoord2f(0.0f, tex);				glVertex3f(x / 12.0f, (y+1) / 12.0f, 0.0f);			}		}	glEnd();	// Render player	glLoadIdentity();		glBindTexture(GL_TEXTURE_2D, textures[1]); // Player's texture	glBegin(GL_QUADS);				int animstate = 0;		int direction = 0;		GLfloat x = direction / 4.0f;		GLfloat y = animstate / 4.0f;		const GLfloat d = 1.0f / 4.0f;				glTexCoord2f(x,  y+d);		glVertex3f(0.0f, 0.0f, 0.0f);		glTexCoord2f(x+d,y+d);		glVertex3f(1.0f, 0.0f, 0.0f);		glTexCoord2f(x+d,y);		glVertex3f(1.0f, 1.0f, 0.0f);		glTexCoord2f(x,  y);		glVertex3f(0.0f, 1.0f, 0.0f);	glEnd();		/* Flip to screen */	SDL_GL_SwapBuffers();}/* OpenGL Initialisation */bool initGL() {	if (!loadTextures()) return false;	glViewport(0, 0, SCR_WIDTH, SCR_HEIGHT);	glEnable(GL_TEXTURE_2D);	glShadeModel(GL_SMOOTH);	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);	glClearDepth(1.0f);		glEnable(GL_DEPTH_TEST);	glDepthFunc(GL_LEQUAL);	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Enable RGBA Alpha blending	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);		glEnable(GL_BLEND);	// Set up projection matrix	glMatrixMode(GL_PROJECTION);	glLoadIdentity();	gluPerspective_(180.0, ((double)SCR_WIDTH)/((double)SCR_HEIGHT), -10.0, 100.0);	// Set up Modelview matrix	glMatrixMode(GL_MODELVIEW);	glLoadIdentity();	// Wireframe mode	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);	return true;}