// 3D graphics engine framework
// by Ty Guenley

#include "SDL/SDL.h"
#include "SDL/SDL_opengl.h"

#include <stdio.h>
#include <cmath>
//May need to be changed to whatever the math library is called on your machine

const double PI = 3.1415926535;
const double mouseSensitivity = .1;

struct coord3 {
	double x;
	double y;
	double z;
}

coord3 camPosition;

camPosition.x = 0;
camPosition.y = 0;
camPosition.z = 10;

int mousex, mousey;

double rotationAngle = 0, tiltAngle = 0;

//Timing variables
double lastTime, elapsedTime = .01;

int main(int argc, char *argv[]) {
    
    SDL_Surface *screen;
    float Rotate=0.0f; // A rotation value to be used to spin our polygon
    glClearColor(0,0,0,0);
    
    if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
        printf("Unable to initialize SDL: %s\n", SDL_GetError());
        return 1;
    }

    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*

    screen = SDL_SetVideoMode( 800, 600, 16, SDL_OPENGL ); // *changed*
    if ( !screen ) {
		printf("Unable to set video mode: %s\n", SDL_GetError());
		return 1;
	}
	
    
    // Setup our screen
    //glViewport(0,0,800,600);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f,800.0f/600.0f,1.0f,500.0f);
    glMatrixMode(GL_MODELVIEW);
    
    // Ensure correct display of polygons
    glEnable(GL_CULL_FACE);
    glEnable(GL_DEPTH_TEST);
    glDepthMask(GL_TRUE);

    SDL_WarpMouse(400, 300);
    lastTime = SDL_GetTicks();

    int done = 0;
    
    // SDL_ShowCursor(SDL_DISABLE); // disable cursor

    // This loop will run until Esc is pressed
    while(done == 0) {
        SDL_Event event;
        
        while ( SDL_PollEvent(&event) ) {
            if ( event.type == SDL_QUIT ) {  done = 1;  }
            
            // key events
            if ( event.type == SDL_KEYDOWN ) {
                if ( event.key.keysym.sym == SDLK_ESCAPE ) { done = 1; } // quit on escape
            }
        }

	//Get mouse coordinates
	SDL_GetMouseState(mousex, mousey);

	//Adjust our camera view based on how the mouse moved
	rotationAngle += (mousex - 400) * mouseSensitivity * elapsedTime;
	tiltAngle -= (mousey - 400) * mouseSensitivity * elapsedTime;

	//Limit camera tilt
	if (tiltAngle > PI/2) tiltAngle = PI/2;
	if (tiltAngle < -PI/2) tiltAngle = -PI/2;
        
        SDL_WarpMouse(400,300); // set mouse to center of screen
        
        Uint8 *keystate = SDL_GetKeyState(NULL);
        if ( keystate[SDLK_s] ) {
		camPosition.x += cos(rotationAngle) * 4 * elapsedTime;
		camPosition.z += sin(rotationAngle) * 4 * elapsedTime;
	}
        if ( keystate[SDLK_w] ) {
		camPosition.x -= cos(rotationAngle) * 4 * elapsedTime;
		camPosition.z -= sin(rotationAngle) * 4 * elapsedTime;
	}
        
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear screen and z-buffer
        glLoadIdentity(); // Reset current matrix (Modelview)
        
        // set camera angle
        gluLookAt (camPosition.x, camPosition.y, camPosition.z, camPosition.x + cos(rotationAngle), camPosition.y + sin(tiltAngle), camPosition.z + sin(rotationAngle), 0, 1, 0);
 
        // Do our rotations
        glTranslatef(0.0f,0.0f,-5.0f);
        glRotatef(Rotate,0.0f,0.0f,1.0f);
        glRotatef(Rotate,1.0f,0.6f,0.0f);
    
        // Draw the top and bottom faces
        glBegin(GL_QUADS);
            glColor3f(1.0f,0.0f,0.0f); // Red
            glVertex3f(-1.0f, 1.0f, 1.0f);
            glVertex3f( 1.0f, 1.0f, 1.0f);
            glVertex3f( 1.0f, 1.0f,-1.0f);
            glVertex3f(-1.0f, 1.0f,-1.0f);
        
            glColor3f(0.0f,0.0f,1.0f); // Blue
            glVertex3f(-1.0f,-1.0f, 1.0f);
            glVertex3f(-1.0f,-1.0f,-1.0f);
            glVertex3f( 1.0f,-1.0f,-1.0f);
            glVertex3f( 1.0f,-1.0f, 1.0f);
        glEnd();
    
        // Draw the side faces
        glBegin(GL_TRIANGLE_STRIP);
            glColor3f(1.0f,1.0f,1.0f); // White
            glVertex3f(-1.0f, 1.0f, 1.0f);
            glVertex3f(-1.0f,-1.0f, 1.0f);
            glVertex3f( 1.0f, 1.0f, 1.0f);
            glColor3f(0.0f,1.0f,0.0f); // Green
            glVertex3f( 1.0f,-1.0f, 1.0f);
            glColor3f(1.0f,1.0f,0.0f); // Yellow
            glVertex3f( 1.0f, 1.0f,-1.0f);
            glColor3f(0.0f,1.0f,1.0f); // Aqua?
            glVertex3f( 1.0f,-1.0f,-1.0f);
            glColor3f(0.6f,0.6f,0.6f); // Gray
            glVertex3f(-1.0f, 1.0f,-1.0f);
            glColor3f(0.1f,0.1f,0.1f); // Dark Gray
            glVertex3f(-1.0f,-1.0f,-1.0f);
            glColor3f(0.0f,0.0f,1.0f); // Blue
            glVertex3f(-1.0f, 1.0f, 1.0f);
            glColor3f(1.0f,0.0f,1.0f); // Red
            glVertex3f(-1.0f,-1.0f, 1.0f);
        glEnd();
    
        // Add to the rotation for next frame 
        Rotate+=0.05f;
    
        // Show our cube
        SDL_GL_SwapBuffers();

	//Calculate elapsed time since last frame completed
	elapsedTime = SDL_GetTicks() - lastTime;
	lastTime = SDL_GetTicks();
	
    }
}