nuclear@0: #include <stdio.h>
nuclear@0: #include <stdlib.h>
nuclear@0: #include <assert.h>
nuclear@0: #include "opengl.h"
nuclear@0: 
nuclear@0: static bool init();
nuclear@0: static void cleanup();
nuclear@0: static void resize_rtarget(int xsz, int ysz);
nuclear@0: static void update_rect(int x, int y, int xsz, int ysz, float *pixels);
nuclear@0: static void display();
nuclear@0: static void reshape(int x, int y);
nuclear@0: static void keyb(unsigned char key, int x, int y);
nuclear@0: static void mouse(int bn, int st, int x, int y);
nuclear@0: static int next_pow2(int x);
nuclear@0: 
nuclear@0: static int width, height, rtex_width, rtex_height;
nuclear@0: static unsigned int rtex;
nuclear@0: 
nuclear@0: int main(int argc, char **argv)
nuclear@0: {
nuclear@0: 	glutInitWindowSize(1024, 600);
nuclear@0: 	glutInit(&argc, argv);
nuclear@0: 	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
nuclear@0: 	glutCreateWindow("erebus OpenGL frontend");
nuclear@0: 
nuclear@0: 	glutDisplayFunc(display);
nuclear@0: 	glutReshapeFunc(reshape);
nuclear@0: 	glutKeyboardFunc(keyb);
nuclear@0: 	glutMouseFunc(mouse);
nuclear@0: 
nuclear@0: 	if(!init()) {
nuclear@0: 		return 1;
nuclear@0: 	}
nuclear@0: 	atexit(cleanup);
nuclear@0: 
nuclear@0: 	glutMainLoop();
nuclear@0: }
nuclear@0: 
nuclear@0: static bool init()
nuclear@0: {
nuclear@0: 	return true;
nuclear@0: }
nuclear@0: 
nuclear@0: static void cleanup()
nuclear@0: {
nuclear@0: }
nuclear@0: 
nuclear@0: static void resize_rtarget(int xsz, int ysz)
nuclear@0: {
nuclear@0: 	static unsigned char *defpix;
nuclear@0: 
nuclear@0: 	width = xsz;
nuclear@0: 	height = ysz;
nuclear@0: 
nuclear@0: 	if(xsz <= rtex_width && ysz <= rtex_height) {
nuclear@0: 		return;
nuclear@0: 	}
nuclear@0: 	rtex_width = next_pow2(xsz);
nuclear@0: 	rtex_height = next_pow2(ysz);
nuclear@0: 
nuclear@0: 	printf("resizing framebuffer texture: %dx%d\n", rtex_width, rtex_height);
nuclear@0: 
nuclear@0: 	if(!rtex) {
nuclear@0: 		glGenTextures(1, &rtex);
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	delete [] defpix;
nuclear@0: 	defpix = new unsigned char[rtex_width * rtex_height * 4];
nuclear@0: 	unsigned char *ptr = defpix;
nuclear@0: 	for(int i=0; i<rtex_height; i++) {
nuclear@0: 		for(int j=0; j<rtex_width; j++) {
nuclear@0: 			bool chess = ((i >> 4) & 1) == ((j >> 4) & 1);
nuclear@0: 
nuclear@0: 			int val = chess ? 64 : 48;
nuclear@0: 
nuclear@0: 			*ptr++ = val;
nuclear@0: 			*ptr++ = val;
nuclear@0: 			*ptr++ = val;
nuclear@0: 			*ptr++ = 255;
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	glBindTexture(GL_TEXTURE_2D, rtex);
nuclear@0: 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
nuclear@0: 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
nuclear@0: 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F_ARB, rtex_width, rtex_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, defpix);
nuclear@0: }
nuclear@0: 
nuclear@0: static void update_rect(int x, int y, int xsz, int ysz, float *pixels)
nuclear@0: {
nuclear@0: 	glBindTexture(GL_TEXTURE_2D, rtex);
nuclear@0: 	glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, xsz, ysz, GL_RGBA, GL_FLOAT, pixels);
nuclear@0: }
nuclear@0: 
nuclear@0: static void display()
nuclear@0: {
nuclear@0: 	glBindTexture(GL_TEXTURE_2D, rtex);
nuclear@0: 	glEnable(GL_TEXTURE_2D);
nuclear@0: 
nuclear@0: 	float maxu = (float)width / (float)rtex_width;
nuclear@0: 	float maxv = (float)height / (float)rtex_height;
nuclear@0: 
nuclear@0: 	glBegin(GL_QUADS);
nuclear@0: 	glTexCoord2f(0, maxv); glVertex2f(-1, -1);
nuclear@0: 	glTexCoord2f(maxu, maxv); glVertex2f(1, -1);
nuclear@0: 	glTexCoord2f(maxu, 0); glVertex2f(1, 1);
nuclear@0: 	glTexCoord2f(0, 0); glVertex2f(-1, 1);
nuclear@0: 	glEnd();
nuclear@0: 
nuclear@0: 	glDisable(GL_TEXTURE_2D);
nuclear@0: 
nuclear@0: 	glutSwapBuffers();
nuclear@0: 	assert(glGetError() == GL_NO_ERROR);
nuclear@0: }
nuclear@0: 
nuclear@0: static void reshape(int x, int y)
nuclear@0: {
nuclear@0: 	glViewport(0, 0, x, y);
nuclear@0: 	resize_rtarget(x, y);
nuclear@0: }
nuclear@0: 
nuclear@0: static void keyb(unsigned char key, int x, int y)
nuclear@0: {
nuclear@0: 	switch(key) {
nuclear@0: 	case 27:
nuclear@0: 		exit(0);
nuclear@0: 	}
nuclear@0: }
nuclear@0: 
nuclear@0: static void mouse(int bn, int st, int x, int y)
nuclear@0: {
nuclear@0: }
nuclear@0: 
nuclear@0: static int next_pow2(int x)
nuclear@0: {
nuclear@0: 	int res = 2;
nuclear@0: 	while(res < x) {
nuclear@0: 		res <<= 1;
nuclear@0: 	}
nuclear@0: 	return res;
nuclear@0: }