#include "stdafx.h"

#define GL_PI 3.1415f

#define	checkImageWidth 256
#define	checkImageHeight 256
#define subImageWidth 64
#define subImageHeight 64

static GLubyte checkImage[checkImageHeight][checkImageWidth][4];
static GLubyte otherImage[checkImageHeight][checkImageWidth][4];

static GLubyte subImage[subImageHeight][subImageWidth][4];

static GLuint texName[1];

GLfloat colors[][3] = { { 0.0, 0.0, 0.0 },{ 1.0, 0.0, 0.0 },
{ 1.0, 1.0, 0.0 },{ 0.0, 1.0, 0.0 },{ 0.0, 0.0, 1.0 },
{ 1.0, 0.0, 1.0 },{ 1.0, 1.0, 1.0 },{ 0.0, 1.0, 1.0 } };

#define YGROUND  250.

GLfloat pis[4] = { 0., 1., 0., YGROUND },
foco[4] = { 75., 150., -35., 1.f }, msobmra[16];

GLfloat ALFA = 0.75f;
GLfloat ambientLight[] = { 0.1f, 0.1f, 0.1f, 1.0f }, 
diffuseLight[] = { 0.9f, 0.9f, 0.9f, 1.0f },
lmodel_ambient[] = { 0.4, 0.4, 0.4, 1.0 },
specular[] = { 1.0f, 1.0f, 1.0f, 1.0f }, 

specref[] = { 1.0f, 1.0f, 1.0f, 1.0f };
GLfloat local_view[] = { 0.0 };

GLfloat mat_diffuse[] = { 0.8, 0.5, 0.1, 1.0 };
GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };	
GLfloat high_shininess[] = { 100.0 };
	
GLfloat xRot = 0.45f;
GLfloat yRot = 0.35f;

GLboolean	bCull = (GLboolean)true,
bDepth = (GLboolean)true,
bOutline = (GLboolean)true,
bShade = (GLboolean)true;

#define CX				0.0f
#define CY				0.0f
#define CZ				0.0f
GLfloat ex = 0.0f;
GLfloat ey = 100.0f;
GLfloat ez = -700.0f;
GLfloat cx = CX, cy = CY, cz = CZ;

GLfloat delta = 0.01f;
GLfloat deltaR = 0.01f;
#define DELTATRANS		0.05f
GLfloat deltatrans = DELTATRANS;


void normalize(GLfloat v[3]) {
	GLfloat d = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
	if (d == 0.0) { exit(100); return; } // wrong input exit
	v[0] /= d; v[1] /= d; v[2] /= d;
}
void normcrossprod(GLfloat v1[3], GLfloat v2[3], GLfloat out[3])
{
	out[0] = v1[1] * v2[2] - v1[2] * v2[1]; out[1] = v1[2] * v2[0] - v1[0] * v2[2];
	out[2] = v1[0] * v2[1] - v1[1] * v2[0];	normalize(out);
}

void gltGetNormalVector(GLfloat v0[3], GLfloat //build normal 'norm'
	v1[3], GLfloat v2[3], GLfloat norm[3])	// by the triangle vrtices
{
	GLfloat d1[3], d2[3];
	for (int j = 0; j < 3; j++) {
		d1[j] = v0[j] - v1[j];
		d2[j] = v1[j] - v2[j];
	}
	normcrossprod(d1, d2, norm);
}

void makeCheckImages(void)
{
	int i, j, c;

	for (i = 0; i < checkImageHeight; i++) {
		for (j = 0; j < checkImageWidth; j++) {
			c = ((((i & 0x8) == 0) ^ ((j & 0x8)) == 0)) * 255;
			checkImage[i][j][0] = (GLubyte)c;   checkImage[i][j][1] = (GLubyte)c;
			checkImage[i][j][2] = (GLubyte)c;   checkImage[i][j][3] = (GLubyte)255;

			c = ((((i & 0x10) == 0) ^ ((j & 0x10)) == 0)) * 255;
			otherImage[i][j][0] = (GLubyte)0;   otherImage[i][j][1] = (GLubyte)0;
			otherImage[i][j][2] = (GLubyte)c;   otherImage[i][j][3] = (GLubyte)255;
		}
	}

	for (i = 0; i < subImageHeight; i++) {
		for (j = 0; j < subImageWidth; j++) {
			c = ((((i & 0x4) == 0) ^ ((j & 0x4)) == 0)) * 255;
			subImage[i][j][0] = (GLubyte)c;	subImage[i][j][1] = (GLubyte)0;
			subImage[i][j][2] = (GLubyte)0;	subImage[i][j][3] = (GLubyte)255;
		}
	}
}


void unit_square() {
	glBegin(GL_QUADS);
	glNormal3f(0., 0., 1. /*-1.?*/ ); 
	glVertex2f(-1., -1.);
	glVertex2f(1., -1.);
	glVertex2f(1., 1.);
	glVertex2f(-1., 1.);
	glEnd();
}
void unit_square1() {
	glBegin(GL_QUADS);
	glNormal3f(0., 0., 1. /*-1.?*/);
	glColor4f(1., 0., 0., ALFA);
	glVertex2f(-1., -1.);
	glVertex2f(1., -1.);
	glVertex2f(1., 1.);
	glVertex2f(-1., 1.);
	glEnd();
}


void unit_square_con_textura() {

	glEnable(GL_TEXTURE_2D);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
	glBindTexture(GL_TEXTURE_2D, texName[0]);
	glBegin(GL_QUADS);

	glTexCoord2f(0.0, 0.0);  glVertex2f(-1., -1.); //glVertex3f(400.0f, -150.0f, -700.0f); //glVertex3f(-2.0, -1.0, 0.0);
	glTexCoord2f(0.0, 1.0);  glVertex2f(1., -1.); //glVertex3f(-400.0f, -150.0f, -700.0f); //glVertex3f(-2.0, 1.0, 0.0);

	glTexCoord2f(1.0, 1.0);   glVertex2f(1., 1.); //glVertex3f(-400.0f, -150.0f, 200.0f); //glVertex3f(0.0, 1.0, 0.0);
	glTexCoord2f(1.0, 0.0);   glVertex2f(-1., 1.);// glVertex3f(400.0f, -150.0f, 200.0f);//glVertex3f(0.0, -1.0, 0.0);

	glEnd();

	glDisable(GL_TEXTURE_2D);
}

void rayas()
{
	glBegin(GL_LINES);
	int i;
	for (i = 0; i<11; i++) {
		glVertex2f(-1., -1. + i*2. / 10.);
		glVertex2f(1., -1. + i*2. / 10.);
	}
	for (i = 0; i<11; i++) {
		glVertex2f(1. - i*2. / 10., -1.);
		glVertex2f(1. - i*2. / 10., 1.);
	}
	glEnd();
}

void piso() {
	glPushMatrix();
	glTranslatef(0, -pis[3], 0);
	glRotatef(270, 1.0f, 0.0f, 0.0f);
	glScalef(150., 150., 150.);
	glColor4f(0.75, 0.75, 0.75, ALFA);
	unit_square();
	glColor4f(0., 0., 0., ALFA);
	rayas();
	glPopMatrix();
}

void luz() {
/*Esta funcion renderiza fuente luz y ademas
mediante la 2a instruccion configura su posicion
para el modelo de Phong*/
	glColor4f(1., 1., 0., 1.);
	glLightfv(GL_LIGHT0, GL_POSITION, foco/*lightPos*/);
	glPushMatrix();
	glTranslatef(foco[0], foco[1], foco[2]);
	glScalef(10., 10., 10.);
	glutSolidSphere(1, 20, 20);
	glPopMatrix();
}


void colorcube2(void) {
	glPushMatrix();
	glScalef(50., 50., 50.);
	//1a cara
	glPushMatrix();
	glTranslatef(0., 0., 1.);
	//glColor4f(1.0, 0.0, 0.0, ALFA);
	unit_square1();
	glPopMatrix();
	//2a cara
	glPushMatrix();
	glRotatef(90., 0., 1., 0.);
	glTranslatef(0., 0., 1.);
	//glColor4f(1./*0.0*/, 0./*1.0*/, 0.0, ALFA);// para la iluminacion
	unit_square1();
	glPopMatrix();

	//3a cara
	glPushMatrix();
	glRotatef(180., 0., 1., 0.);
	glTranslatef(0., 0., 1.);
	unit_square_con_textura();
	glPopMatrix();

	//4a cara
	glPushMatrix();
	glRotatef(90., 1., 0., 0.);
	glTranslatef(0., 0., 1.);	
	unit_square1();
	glPopMatrix();
	//etc. ...
	glPopMatrix();
}

void cubo_sin_color(void) {
	glPushMatrix();
	glScalef(50., 50., 50.);
	//1a cara
	glPushMatrix();
	glTranslatef(0., 0., 1.);

	unit_square();
	glPopMatrix();
	//2a cara
	glPushMatrix();
	glRotatef(90., 0., 1., 0.);
	glTranslatef(0., 0., 1.);

	unit_square();
	glPopMatrix();

	//3a cara
	glPushMatrix();
	glRotatef(180., 0., 1., 0.);
	glTranslatef(0., 0., 1.);
	unit_square();
	glPopMatrix();


	//4a cara
	glPushMatrix();
	glRotatef(90., 1., 0., 0.);
	glTranslatef(0., 0., 1.);
	unit_square();
	glPopMatrix();

	//etc. ...
	glPopMatrix();
}


///////////////////////////////////////////////////////////
void gltMakeShadowMatrix(GLfloat vPlaneEquation[], GLfloat vLightPos[], GLfloat destMat[])
{
	GLfloat dot;

	// Dot product of plane and light position
	dot = vPlaneEquation[0] * vLightPos[0] + vPlaneEquation[1] * vLightPos[1] +
		vPlaneEquation[2] * vLightPos[2] + vPlaneEquation[3] * vLightPos[3];

	// Now do the projection
	// First column
	destMat[0] = dot - vLightPos[0] * vPlaneEquation[0];
	destMat[4] = 0.0f - vLightPos[0] * vPlaneEquation[1];
	destMat[8] = 0.0f - vLightPos[0] * vPlaneEquation[2];
	destMat[12] = 0.0f - vLightPos[0] * vPlaneEquation[3];

	// Second column
	destMat[1] = 0.0f - vLightPos[1] * vPlaneEquation[0];
	destMat[5] = dot - vLightPos[1] * vPlaneEquation[1];
	destMat[9] = 0.0f - vLightPos[1] * vPlaneEquation[2];
	destMat[13] = 0.0f - vLightPos[1] * vPlaneEquation[3];

	// Third Column
	destMat[2] = 0.0f - vLightPos[2] * vPlaneEquation[0];
	destMat[6] = 0.0f - vLightPos[2] * vPlaneEquation[1];
	destMat[10] = dot - vLightPos[2] * vPlaneEquation[2];
	destMat[14] = 0.0f - vLightPos[2] * vPlaneEquation[3];

	// Fourth Column
	destMat[3] = 0.0f - vLightPos[3] * vPlaneEquation[0];
	destMat[7] = 0.0f - vLightPos[3] * vPlaneEquation[1];
	destMat[11] = 0.0f - vLightPos[3] * vPlaneEquation[2];
	destMat[15] = dot - vLightPos[3] * vPlaneEquation[3];
}

void SombraCubo() {
	//glLightfv(GL_LIGHT0, GL_POSITION, foco);
	glPushMatrix();
	gltMakeShadowMatrix(pis, foco, msobmra);
	glMultMatrixf(msobmra);
	glColor4f(0.7, 0.7, 0.7, ALFA);
	cubo_sin_color();
	glPopMatrix();
}


void SetupRC()
{

	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_SMOOTH);

	// Clockwise-wound polygons are front facing; this is reversed
	// because we are using triangle fans


	makeCheckImages();
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
	glGenTextures(1, texName);
	glBindTexture(GL_TEXTURE_2D, texName[0]);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHeight,
		0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);

	glTexSubImage2D(GL_TEXTURE_2D, 0, 48, 170, subImageWidth,
		subImageHeight, GL_RGBA, GL_UNSIGNED_BYTE, subImage);

	glTexSubImage2D(GL_TEXTURE_2D, 0, 48, 48, subImageWidth,
		subImageHeight, GL_RGBA, GL_UNSIGNED_BYTE, subImage);

	glTexSubImage2D(GL_TEXTURE_2D, 0, 170, 48, subImageWidth,
		subImageHeight, GL_RGBA, GL_UNSIGNED_BYTE, subImage);

	glTexSubImage2D(GL_TEXTURE_2D, 0, 170, 170, subImageWidth,
		subImageHeight, GL_RGBA, GL_UNSIGNED_BYTE, subImage);

	// Set up and enable light 0
	glFrontFace(GL_CCW);
	glEnable(GL_LIGHTING);
	glEnable(GL_CULL_FACE);
	glEnable(GL_DEPTH_TEST);
	glPolygonMode(GL_BACK, GL_FILL);
	GLfloat att[] = {1.};
	glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
	glLightfv(GL_LIGHT0, GL_SPECULAR, specular);
	//glLightfv(GL_LIGHT0, GL_QUADRATIC_ATTENUATION, att);
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
	glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

	glEnable(GL_LIGHT0);
	
	//glLightfv(GL_LIGHT0, GL_POSITION, foco); <- se llama en luz()
	
	// Enable color tracking
	glEnable(GL_COLOR_MATERIAL);
	// Front material ambient and diffuse colors track glColor
	glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);

	// All materials hereafter have full specular reflectivity
	// with a high shine
		glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
		glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
		glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);	
}


void Stencil_Config() {
	// turning off writing to the color buffer and depth buffer so we only
	// write to stencil buffer
	glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
	glDepthMask(GL_FALSE);

	// enable stencil buffer
	glEnable(GL_STENCIL_TEST);

	// write a one to the stencil buffer everywhere we are about to draw
	glStencilFunc(GL_ALWAYS, 1, 0xFFFFFFFF);

	// this is to always pass a one to the stencil buffer where we draw
	glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE);

	// render the plane which the shadow will be on
	// color and depth buffer are disabled, only the stencil buffer
	// will be modified
	piso();
	// turn the color and depth buffers back on
	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
	glDepthMask(GL_TRUE);
	// until stencil test is diabled, only write to areas where the
	// stencil buffer has a one. This is to draw the shadow only on
	// the floor.
	glStencilFunc(GL_EQUAL, 1, 0xFFFFFFFF);
	// don't modify the contents of the stencil buffer
	glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
}

// Called to draw scene

void RenderScene(void)
{
	// Reset coordinate system

	glLoadIdentity();
	gluLookAt(ex, ey, ez, cx, cy, cz, 0.0, 1.0, 0.0);

	GLfloat x, y, angle;         // Storage for coordinates and angles
	int iPivot = 1;            // Used to flag alternating colors

							   // Clear the window and the depth buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
	//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// Turn culling on if flag is set
	if (bCull)   glEnable(GL_CULL_FACE);
	else        glDisable(GL_CULL_FACE);

	// Enable depth testing if flag is set
	if (bDepth)  glEnable(GL_DEPTH_TEST);
	else        glDisable(GL_DEPTH_TEST);

	// Draw the front /*back*/ side as a wireframe only, if flag is set
	if (bOutline)glPolygonMode(/*GL_BACK*/GL_FRONT, GL_LINE);
	else        glPolygonMode(/*GL_BACK*/GL_FRONT, GL_FILL);

	glPushMatrix();
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);
	
	glFrontFace(GL_CW); //cambio de orientacion
						//para ver objetos reflejados

	glPushMatrix();
		glTranslatef(0., -pis[3], 0.); //trabnsformaciones
		glScalef(1., -1., 1.);         // de
		glTranslatef(0., pis[3], 0.);  //reflejo

		Stencil_Config();

		colorcube2();    //dibujar el mundo
		luz();           //en espejo
	glPopMatrix();
	//glDisable(GL_LIGHTING);

	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
	glDisable(GL_DEPTH_TEST); // para luchar con errores de redondeo
	
	glFrontFace(GL_CCW);
	SombraCubo();       //dibujar sombra mezclandola con reflejo
	if (bDepth)  glEnable(GL_DEPTH_TEST);
	else        glDisable(GL_DEPTH_TEST);
	glDisable(GL_STENCIL_TEST);
	if (bOutline)glPolygonMode(/*GL_BACK*/GL_FRONT, GL_LINE);
	else         glPolygonMode(/*GL_BACK*/GL_FRONT, GL_FILL);
		
	piso();     //dibujar piso mezclandolo con reflejo+sombra

	glDisable(GL_BLEND);

	colorcube2();
	luz();
	
	glPopMatrix();
	// Flush drawing commands
	glFlush();// glutSwapBuffers();
}

// Called by GLUT library when the window has changed size

void ChangeSize(GLsizei w, GLsizei h)
{    // Set Viewport to window dimensions
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	//glOrtho (-100.0, 100.0, -100, 100, -270.0, 270.0);
	//glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
	gluPerspective(60.0, 1.0, 1.5, 2500.0);
	glMatrixMode(GL_MODELVIEW);
}

void SpecialKeys(int key, int x, int y)
{
	GLfloat dx, dy, dz, dx0, dy0, dz0;

	if (key == GLUT_KEY_UP)
	{//increase distance from camera to origin
		ex *= (1.0f + deltaR);  ey *= (1.0f + deltaR);    ez *= (1.0f + deltaR);
	}

	if (key == GLUT_KEY_DOWN)
	{//reduce distance from camera to origin (close up)
		ex *= (1.0f - deltaR); ey *= (1.0f - deltaR);    ez *= (1.0f - deltaR);
	}

	if (key == GLUT_KEY_LEFT)
		//Rotate camera around origin in Oxz plane
	{
		dx = -ez;     dz = ex;
		GLfloat s = sqrtf(ex*ex + ey*ey + ez*ez);
		ex += delta*dx;       ez += delta*dz;
		GLfloat s1 = sqrtf(ex*ex + ey*ey + ez*ez) / s;
		ex /= s1;    ey /= s1;    ey /= s1;
	}

	if (key == GLUT_KEY_RIGHT)
		//Rotate camera around origin in Oxz plane
	{
		dx = -ez;     dz = ex;
		GLfloat s = sqrtf(ex*ex + ey*ey + ez*ez);
		ex -= delta*dx;          ez -= delta*dz;
		GLfloat s1 = sqrtf(ex*ex + ey*ey + ez*ez) / s;
		ex /= s1;    ey /= s1;    ey /= s1;
	}

	if (key == GLUT_KEY_F1) bCull = !bCull;
	if (key == GLUT_KEY_F2)bDepth = !bDepth;
	if (key == GLUT_KEY_F3)bOutline = !bOutline;
	if (key == GLUT_KEY_F4)
	{
		bShade = !bShade;
		if (bShade) { glShadeModel(GL_FLAT); }
		else { glShadeModel(GL_SMOOTH); }	
	}

	if (key == GLUT_KEY_F5)//Rotate camera around origin in Oyz plane
	{
		dy = -ez;     dz = ey;
		GLfloat s = sqrtf(ex*ex + ey*ey + ez*ez);
		ey -= delta*dy;          ez -= delta*dz;
		GLfloat s1 = sqrtf(ex*ex + ey*ey + ez*ez) / s;
		ex /= s1;    ey /= s1;    ey /= s1;
	}

	if (key == GLUT_KEY_F6)//Rotate camera around origin in Oyz plane
	{
		dy = -ez;     dz = ey;
		GLfloat s = sqrtf(ex*ex + ey*ey + ez*ez);
		ey += delta*dy;          ez += delta*dz;
		GLfloat s1 = sqrtf(ex*ex + ey*ey + ez*ez) / s;
		ex /= s1;    ey /= s1;    ey /= s1;
	}
	//////////
	if (key == GLUT_KEY_F7)//Move light toward the center of ground 
	{		
		dx = cx -  foco[0]; 
		dy = cy -  foco[1];    
		dz = cz -  foco[2];
		dx *= (1.0 - deltatrans); dy *= (1.0 - deltatrans);
		dz *= (1.0 - deltatrans);
		 foco[0] = cx - dx;  
		 foco[1] = cy - dy; 
		 foco[2] = cz - dz;
		// Calculate new projection matrix to draw shadow on the ground
	}
	if (key == GLUT_KEY_F8)//Move light outward the center of ground 
	{		
		dx = cx -  foco[0]; 
		dy = cy -  foco[1];    
		dz = cz -  foco[2];

		dx /= (1.0 - deltatrans); dy /= (1.0 - deltatrans);
		dz /= (1.0 - deltatrans);
		 foco[0] = cx - dx;  
		 foco[1] = cy - dy; 
		 foco[2] = cz - dz;	
	}

	if (key == GLUT_KEY_F9)//Rotate (+) light  around ... in the vertical plane 
	{		
		dy0 = cz -  foco[2];  
		dz0 =  foco[1] - cy;
		dy = cy -  foco[1];    
		dz = cz -  foco[2];
		GLfloat s = sqrtf(dy*dy + dz*dz);
		dy += delta*dy0;       dz += delta*dz0;
		GLfloat s1 = sqrtf(dy*dy + dz*dz) / s;
		dy /= s1;		dz /= s1;
		 foco[1] = cy - dy; 
		 foco[2] = cz - dz;
	}
	if (key == GLUT_KEY_F10)//Rotate (-) light  around ... in the vertical plane 
	{		
		dy0 = cz -  foco[2];  
		dz0 =  foco[1] - cy;
		dy = cy -  foco[1];   
		dz = cz -  foco[2];
		GLfloat s = sqrtf(dy*dy + dz*dz);
		dy -= delta*dy0;       dz -= delta*dz0;
		GLfloat s1 = sqrtf(dy*dy + dz*dz) / s;
		dy /= s1;		dz /= s1;
		 foco[1] = cy - dy; 
		 foco[2] = cz - dz;
	}
	if (key == GLUT_KEY_F11)//Rote light  around ... in the horizontal plane 
	{		
		dy = - foco[2];   
		dz =  foco[0];
		GLfloat s = sqrtf( foco[0] *  foco[0]
			+  foco[1] *  foco[1]
			+  foco[2] *  foco[2]);
		 foco[0] += delta*dy;      	
		 foco[2] += delta*dz;
		GLfloat s1 = sqrtf( foco[0] *  foco[0]
			+  foco[1] *  foco[1]
			+  foco[2] *  foco[2]) / s;
		 foco[0] /= s1;	 foco[1] /= s1;	
		 foco[2] /= s1;	
	}
	if (key == GLUT_KEY_F12)//Move light in horiz. plane  
	{		
		dy =  foco[0];   dz =  foco[2];
		 foco[0] += delta*dy;      	
		 foco[2] += delta*dz;
	}
	// Refresh the Window
	glutPostRedisplay();
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(/*GLUT_DOUBLE*/GLUT_SINGLE | GLUT_RGBA | GLUT_STENCIL | GLUT_DEPTH);	
	glutInitWindowSize(200, 200);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);
	glutDisplayFunc(RenderScene);
	glutReshapeFunc(ChangeSize);
	glutSpecialFunc(SpecialKeys);

	SetupRC();
	glutMainLoop();
	return 0;
}