/*
Compile with :
g++ query.cpp -g -lglfw -lGL -lGLEW -lGLU -o query

*/
#include <GL/glew.h>
#include <GL/glfw.h>
#include <GL/gl.h>
#include <cassert>
#include <iostream>
#include <cmath>
#include <cstdlib>
#include <climits>

GLfloat n[6][3] = {  /* Normals for the 6 faces of a cube. */
  {-1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {1.0, 0.0, 0.0},
  {0.0, -1.0, 0.0}, {0.0, 0.0, 1.0}, {0.0, 0.0, -1.0} };
GLint faces[6][4] = {  /* Vertex indices for the 6 faces of a cube. */
  {0, 1, 2, 3}, {3, 2, 6, 7}, {7, 6, 5, 4},
  {4, 5, 1, 0}, {5, 6, 2, 1}, {7, 4, 0, 3} };
GLfloat v[8][3];  /* Will be filled in with X,Y,Z vertexes. */

void drawBox(void) {
	for (int i = 0; i < 6; i++) {
		glBegin(GL_QUADS);
		glNormal3fv(&n[i][0]);
		glVertex3fv(&v[faces[i][0]][0]);
		glVertex3fv(&v[faces[i][1]][0]);
		glVertex3fv(&v[faces[i][2]][0]);
		glVertex3fv(&v[faces[i][3]][0]);
		glEnd();
	}
}

#define CHECK_GL_ERROR {GLenum err = glGetError(); if (err != GL_NO_ERROR) { std::cout << "Error : " << gluErrorString(err) << std::endl; assert(false); }}

float randf() {
	return rand() / (float)INT_MAX;
}

int main(int argc, char** argv) {
	glfwInit();

	int num_queries = 50;
	if (argc > 1) num_queries = atoi(argv[1]);

	int w = 640, h =400 ;
	glfwOpenWindow(w, h, 8, 8, 8, 8, 24, 8, GLFW_WINDOW);

	glewInit();
    
	// setup camera
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(70, w / (float)h, 0.1, 200);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(0.0, 0.0, 5.0,  /* eye is at (0,0,5) */
			0.0, 0.0, 0.0,      /* center is at (0,0,0) */
			0.0, 1.0, 0.);      /* up is in positive Y direction */
	glClearColor(1,1,1,1);
	glColor3f(1,0,0);

	/* Setup cube vertex data. */
	v[0][0] = v[1][0] = v[2][0] = v[3][0] = -1;
	v[4][0] = v[5][0] = v[6][0] = v[7][0] = 1;
	v[0][1] = v[1][1] = v[4][1] = v[5][1] = -1;
	v[2][1] = v[3][1] = v[6][1] = v[7][1] = 1;
	v[0][2] = v[3][2] = v[4][2] = v[7][2] = 1;
	v[1][2] = v[2][2] = v[5][2] = v[6][2] = -1;

	
	GLuint queryIds[num_queries];
	glGenQueries(num_queries, queryIds);

   while(true) {
		CHECK_GL_ERROR

		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		gluLookAt(0.0, 0.0, 5.0,  /* eye is at (0,0,5) */
    			0.0, 0.0, 0.0,      /* center is at (0,0,0) */
    			0.0, 1.0, 0.);      /* up is in positive Y direction */

		/* Change cube position */
		glTranslatef(randf(), randf(), randf());
		glRotatef(60, 1.0, 0.0, 0.0);
		glRotatef(-20, 0.0, 0.0, 1.0);

		int prev = -1;
		for(int i=0; i<num_queries; ++i) {
			glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
			glBeginQuery(GL_SAMPLES_PASSED, queryIds[i]);
			drawBox();
			glEndQuery(GL_SAMPLES_PASSED);

			GLint param;
			glGetQueryObjectiv(queryIds[i], GL_QUERY_RESULT, &param);

			if (prev < 0) prev = param;
			else {
				if (prev != param) {
					std::cout << "query error : " << prev << " != " << param << std::endl;
					assert(false);
				}
			}
		}
      
		glfwSwapBuffers();

		if (glfwGetKey( GLFW_KEY_ESC ) || !glfwGetWindowParam( GLFW_OPENED )) break;
	}

	return 0;
}