#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

#include <math.h>
#include <stdlib.h>


#define MAP_X	10
#define MAP_Z	10

int height[10][10] ={
	{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }};

float terrain[10][10][3];
int x, z;
float aspect = 1.0f;
float lx=0.0f,lz=-1.0f;
float camx=0.0f,camz=5.0f;
float angle = 0.0f;

void processSpecialKeys(int key, int xx, int yy)
{

	float fraction = 0.1f;

	switch (key) {
	case GLUT_KEY_LEFT :
		angle -= 0.01f;
		lx = sin(angle);
		lz = -cos(angle);
		break;
	case GLUT_KEY_RIGHT :
		angle += 0.01f;
		lx = sin(angle);
		lz = -cos(angle);
		break;
	case GLUT_KEY_UP :
		camx += lx * fraction;
		camz += lz * fraction;
		break;
	case GLUT_KEY_DOWN :
		camx -= lx * fraction;
		camz -= lz * fraction;
		break;
	}
}


void initializeTerrain()
{
	for (z = 0; z < MAP_Z; z++)
	{
		for (x = 0; x < MAP_X; x++)
		{
			terrain[x][z][0] = (float)(x);
			terrain[x][z][1] = (float)height[x][z];
			terrain[x][z][2] = -(float)(z);
		}
	}
}

void display(void){

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	gluLookAt(	camx, 1.0f, camz,
		camx+lx, 1.0f, camz+lz,
		0.0f, 1.0f, 0.0f);


	glColor4f(1.0, 0.0, 0.0,0.5);

	for (z = 0; z < MAP_Z-1; z++)
	{
		glBegin(GL_TRIANGLE_STRIP);
		for (x = 0; x < MAP_X-1; x++)
		{
			glVertex3f(terrain[x][z][0], terrain[x][z][1], terrain[x][z][2]);

			glVertex3f(terrain[x+1][z][0], terrain[x+1][z][1], terrain[x+1][z][2]);

			glVertex3f(terrain[x][z+1][0], terrain[x][z+1][1], terrain[x][z+1][2]);

			glVertex3f(terrain[x+1][z+1][0], terrain[x+1][z+1][1], terrain[x+1][z+1][2]);
		}
		glEnd();
	}

	glutSwapBuffers();
}

void myInit(){
	initializeTerrain();
	glMatrixMode(GL_PROJECTION);
	glViewport(0, 0, 500, 500);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glMatrixMode(GL_MODELVIEW);
	glClearColor(1.0, 1.0, 1.0, 1.0);


}

void reshape(int w, int h)
{
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	if (w <= h)
		glOrtho(-10.0, 10.0, -5.0 * (GLfloat) h / (GLfloat) w,
		15.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);
	else
		glOrtho(-10.0 * (GLfloat) w / (GLfloat) h,
		10.0 * (GLfloat) w / (GLfloat) h, -5.0, 15.0, -10.0, 10.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

void main(int argc, char** argv){

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutCreateWindow("A3");
	myInit();
	glutReshapeFunc(reshape);
	glutDisplayFunc(display);
	glutSpecialFunc(processSpecialKeys);
	glEnable(GL_DEPTH_TEST);
	glutMainLoop();
}