shadow

#include <gl/glos.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glaux.h>
#include <conio.h>
#include <math.h>

void MakeShadowMatrix(GLfloat points[3][3], GLfloat lightPos[4], GLfloat destMat[4][4])
{
    GLfloat planeCoeff[4];
    GLfloat dot;

    calcNormal(points, planeCoeff);

    planeCoeff[3] = -(planeCoeff[0] * points[2][0] + planeCoeff[1] * points[2][1] + planeCoeff[2] * points[2][2]);

    dot = planeCoeff[0] * lightPos[0] +
        planeCoeff[1] * lightPos[1] +
        planeCoeff[2] * lightPos[2] +
        planeCoeff[3] * lightPos[3];

    destMat[0][0] = dot - lightPos[0] * planeCoeff[0];
    destMat[1][0] = 0.0f - lightPos[0] * planeCoeff[1];
    destMat[2][0] = 0.0f - lightPos[0] * planeCoeff[2];
    destMat[3][0] = 0.0f - lightPos[0] * planeCoeff[3];

    destMat[0][1] = dot - lightPos[1] * planeCoeff[0];
    destMat[1][1] = 0.0f - lightPos[1] * planeCoeff[1];
    destMat[2][1] = 0.0f - lightPos[1] * planeCoeff[2];
    destMat[3][1] = 0.0f - lightPos[1] * planeCoeff[3];

    destMat[0][2] = dot - lightPos[2] * planeCoeff[0];
    destMat[1][2] = 0.0f - lightPos[2] * planeCoeff[1];
    destMat[2][2] = 0.0f - lightPos[2] * planeCoeff[2];
    destMat[3][2] = 0.0f - lightPos[2] * planeCoeff[3];

    destMat[0][3] = dot - lightPos[3] * planeCoeff[0];
    destMat[1][3] = 0.0f - lightPos[3] * planeCoeff[1];
    destMat[2][3] = 0.0f - lightPos[3] * planeCoeff[2];
    destMat[3][3] = 0.0f - lightPos[3] * planeCoeff[3];

}

void CALLBACK deseneaza(void)
{
    GLfloat ambietLight[] = { 0.3f, 0.3f, 0.3f, 1.0f };
    GLfloat diffuseLight[] = { 0.7f, 0.7f, 0.7f, 1.0f };
    GLfloat specuulatLight[] = { 1.0f, 1.0f, 1.0f, 1.0f };
    GLfloat lightPos[] = { 0, 50, -100, 1 };
    GLfloat specref[] = { 1.0f, 1.0f, 1.0f, 1.0f };

    GLfloat mynormal[3];
    GLfloat plan[4][3] = {
        {-500, -50, 500},
        {500, -50, 500},
        {500, -50, -500},
        {-500, -50, -500}
    };
    GLfloat plan_[4][3] = {
        {-500, -49.9, 500},
        {500, -49.9, 500},
        {500, -49.9, -500},
        {-500, -49.9, -500}
    };

    GLfloat shadowMat[4][4];
    GLfloat pi = 3.14159f;
    GLint i, j, lx = 100, ly = 100;

    lightPos[0] = sin(arot[1] * pi * 2 / 360) * 40;
    lightPos[1] = 50;
    lightPos[2] = cos(arot[1] * pi * 2 / 360) * 40 - 150;

    MakeShadowMatrix(plan_, lightPos, shadowMat);

    glEnable(GL_DEPTH_TEST);
    glFrontFace(GL_CCW);

    glEnable(GL_LIGHTING);

    glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
    glLightfx(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
    glLightfx(GL_LIGHT0, GL_SPECULAR, specularLight);
    glLightfx(GL_LIGHT0, GL_POSITION, lightPos);

    glEnable(GL_LIGHT0);

    glEnable(GL_COLOR_MATERIAL);

    glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE)

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMaterialfx(GL_FRONT, GL_SPECULAR, specref);
    glMateriali(GL_FRONT, GL_SHININESS, 128);

    glMatrixMode(GL_MODELVIEW);

    glPushAttrib(GL_LIGHTING_BIT);
    glDisable(GL_LIGHTING);

    glPopMatrix();

    glPushMatrix();

    glMultMatrixf((GLfloat *)shadowMat);
    glColor3f(0, 0.3, 0);
    glTranslatef(0, 0, -150);
    glRotatef(a, 0, 1, 0);
    glRotatef(b, 1, 0, 0);
    auxSolidCube(20.0);

    glPopMatrix();

    glPopAttrib();
    glPushMatrix();

    glColor3f(1, 0, 0);
    glTranslatef(0, 0, -150);
    glRotatef(a, 0, 1, 0);
    glRotatef(b, 1, 0, 0);
    auxSolidCube(20.0);
    glPopMatrix();

    glPushMatrix();
    glColor3f(0, 1.0, 0);
    glBegin(GL_QUADS);
    glVertex3fv(plan[0]);
    glVertex3fv(plan[1]);
    glVertex3fv(plan[2]);
    glVertex3fv(plan[3]);
    glEnd();
    glPopMatrix();

    glFluash();


}

void main()
{
    //initializare modului de afisare –
    //un singur buffer – afisare direct pe ecran –
    //culori după standardul RGBA
    auxInitDisplayMode(AUX_SINGLE | AUX_RGBA);
    //poziţia si dimensiunile ferestrei de afisare
    auxInitPosition(100, 100, 300, 300);
    //initializam fereastra precizand titlul acesteia
    auxInitWindow("Program OpenGL");

    // aici se scrie codul OpenGL pentru afişare
    //stergem fereastra folosind culoarea albastru
    glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    auxMainLoop(deseneaza);
    glFlush();
    // Nu inchide! Asteapta apasarea unei taste
    _getch();
}