/* "cubo del 21-I" con  sombra y blending */

#include "stdafx.h"
#define GL_PI 3.1415f

GLfloat xRot = 0.45f;
GLfloat yRot = 0.35f;
GLboolean bCull = glIsEnabled(GL_CULL_FACE);
GLboolean bDepth = glIsEnabled(GL_DEPTH_TEST);
GLboolean bOutline = (GLboolean)true;

GLenum shademode = GL_FLAT;

GLfloat ex = 0.0f;
GLfloat ey = 0.0f;
GLfloat ez = -120.0f;
GLfloat delta = 0.01f;
GLfloat deltaR = 0.01f;

GLfloat piso[] = { 0, 1/*-1? */, 0, 50 /*-50?*/ };
GLfloat foco[] = { 15., 75., 0. , 1. };
GLfloat MatrizSombra[16];
///////////////////////////////////////////////////////////
GLfloat colors[][3] = { { .5,0.0,0.5 },{ 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 },
{ 0.0,.0,.0 } };


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 cuadrado_fijo() {
	glBegin(GL_POLYGON);
	glVertex2f(1., 1.);
	glVertex2f(1., -1.);
	glVertex2f(-1., -1.);
	glVertex2f(-1., 1.);
	glEnd();
}

void cuadrado_fijo_piso() {
	glBegin(GL_POLYGON);
	glVertex3f(1., 0, 1.);
	glVertex3f(-1., 0, 1.);
	glVertex3f(-1., 0, -1.);
	glVertex3f(1., 0, -1.);
	glEnd();
}

void linea() {
	glBegin(GL_LINES);
	glVertex3f(1, 0, 1);
	glVertex3f(-1, 0, 1);
	glEnd();
}

#define NumLineas 10

void setLineas() {
	glColor3fv(colors[6]);

	for (int i = 0; i > -NumLineas; i--)
	{
		glPushMatrix();
		glTranslatef(0, 0, i*2. / (NumLineas - 1));
		linea();
		glPopMatrix();
	}
}

#define ALFA 0.5 //para blending

void pis() {
	glColor4f(0.6, 0.6, 0.6, ALFA);
	glPushMatrix();
	glTranslatef(0, -piso[3]/*piso[3]?*/, 0);
	glScalef(65., 65., 55.);
	cuadrado_fijo_piso();
	glDisable(GL_DEPTH_TEST);
	setLineas();
	if (bDepth)  glEnable(GL_DEPTH_TEST);
	glPopMatrix();
}

void colorcube_sincolor1(void)
{
	/*1 cara*/
	glPushMatrix();
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*2 cara*/
	glPushMatrix();
	glRotatef(90., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*3 cara*/
	glPushMatrix();
	glRotatef(180., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*4 cara*/
	glPushMatrix();
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*5 cara*/
	glPushMatrix();
	glRotatef(90., 0., 0., 1.);
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*6 cara*/
	glPushMatrix();
	glRotatef(270., 0., 0., 1.);
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
}


void colorcube1(void)
{
	/*1 cara*/
	glColor3fv(colors[0]);
	glPushMatrix();
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
	/*2 cara*/
	glColor3fv(colors[1]);
	glPushMatrix();
	glRotatef(90., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
	/*3 cara*/
	glColor3fv(colors[2]);
	glPushMatrix();
	glRotatef(180., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
	/*4 cara*/
	glColor3fv(colors[3]);
	glPushMatrix();
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
	/*5 cara*/
	glColor3fv(colors[6]);
	glPushMatrix();
	glRotatef(90., 0., 0., 1.);
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();

	/*6 cara*/
	glColor3fv(colors[5]);
	glPushMatrix();
	glRotatef(270., 0., 0., 1.);
	glRotatef(270., 1., 0, 0);
	glTranslatef(0., 0., 1.);
	cuadrado_fijo();
	glPopMatrix();
}

void objetos_del_mundo_sin_color() {
	glPushMatrix();
	glScalef(15., 15., 15.);
	colorcube_sincolor1();
	glPopMatrix();
}

void SombradeCubo(GLfloat datosdeLuz[],
	GLfloat datosdePlano[]) {
	glColor4f(0.3, 0.3, 0.3, ALFA);
	glPushMatrix();
	gltMakeShadowMatrix(datosdePlano,
		datosdeLuz, MatrizSombra);
	glMultMatrixf(MatrizSombra);
	objetos_del_mundo_sin_color(); //Objetos_de_MiMundo();
	glPopMatrix();
}

void objetos_del_mundo() {
	glPushMatrix();
	glScalef(15., 15., 15.);
	colorcube1();
	glPopMatrix();
}

void foc() {
	glColor3fv(colors[2]);
	glPushMatrix();
	glTranslatef(foco[0], foco[1], foco[2]);
	glutSolidSphere(3, 20, 20);
	glPopMatrix();
}

void SetupRC()
{ // Black background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

	// Set color shading model to flat
	glShadeModel(shademode);
	// Clockwise-wound polygons are front facing; this is reversed
	// because we are using triangle fans
	glFrontFace(GL_CW);
}

void RenderScene(void)
{
	// Reset coordinate system
	glLoadIdentity();
	gluLookAt(ex, ey, ez, 0.0, 0.0, 0.0, 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);

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

	// Save matrix state and do the rotation
	glPushMatrix();
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);

	/*piso*/
	pis();

	/*sombra objetos del mundo*/
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glDisable(GL_DEPTH_TEST);
	SombradeCubo(foco, piso);
	if (bDepth)  glEnable(GL_DEPTH_TEST);
	glDisable(GL_BLEND);

	/*objetos del mundo*/
	objetos_del_mundo();

	/*foco*/
	foc();

	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, 500.0);
	glMatrixMode(GL_MODELVIEW);
}

void SpecialKeys(int key, int x, int y)
{
	GLfloat dx, dz;

	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)
	{
		if (shademode == GL_FLAT) { shademode = GL_SMOOTH; }
		else { if (shademode == GL_SMOOTH) { shademode = GL_FLAT; } };
		glShadeModel(shademode);
	}

	//Subir foco
	if (key == GLUT_KEY_F5) {
		foco[1] = (1. + delta)*foco[1]/* + 5*/;
	}
	//Bajar foco
	if (key == GLUT_KEY_F6) {
		foco[1] = (1. - delta)*foco[1]/* - 5*/;
	}
	if (key == GLUT_KEY_F7)
		//Rotate camera around origin in Oyz plane
	{
		GLfloat dy;
		dz = -ey;     dy = ez;
		GLfloat s = sqrtf(ex * ex + ey * ey + ez * ez);
		ez += delta * dz;       ey += delta * dy;
		GLfloat s1 = sqrtf(ex * ex + ey * ey + ez * ez) / s;
		ex /= s1; ey /= s1; ey /= s1;
	}
	if (key == GLUT_KEY_F8)
		//Rotate camera around origin in Oyz plane
	{
		GLfloat dy;
		dz = -ey;     dy = ez;
		GLfloat s = sqrtf(ex * ex + ey * ey + ez * ez);
		ez -= delta * dz;       ey -= delta * dy;
		GLfloat s1 = sqrtf(ex * ex + ey * ey + ez * ez) / s;
		ex /= s1; ey /= s1; ey /= s1;
	}
	/*
	//otra version subir/bajar la camara:

	if (key == GLUT_KEY_F7)xRot -= 1.0f;
	if (key == GLUT_KEY_F8)xRot += 1.0f;*/

	// Refresh the Window
	glutPostRedisplay();
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(/*GLUT_DOUBLE*/GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(600, 600);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);
	glutDisplayFunc(RenderScene);
	glutReshapeFunc(ChangeSize);
	glutSpecialFunc(SpecialKeys);
	SetupRC();
	glutMainLoop();
	return 0;
}