// SphereWorld.c
// OpenGL SuperBible
// Demonstrates an immersive 3D environment using actors
// and a camera. This version adds lights and material properties
// and shadows.
// Program by Richard S. Wright Jr.

#include "../../Common/OpenGLSB.h"	// System and OpenGL Stuff
#include "../../Common/GLTools.h"	// OpenGL toolkit
#include <math.h>

#define NUM_SPHERES      30
GLTFrame    spheres[NUM_SPHERES];
GLTFrame    frameCamera;

// Light and material Data
GLfloat fLightPos[4]   = { -100.0f, 100.0f, 50.0f, 1.0f };  // Point source
GLfloat fNoLight[] = { 0.0f, 0.0f, 0.0f, 0.0f };
GLfloat fLowLight[] = { 0.25f, 0.25f, 0.25f, 1.0f };
GLfloat fBrightLight[] = { 1.0f, 1.0f, 1.0f, 1.0f };

GLTMatrix mShadowMatrix;


        
//////////////////////////////////////////////////////////////////
// This function does any needed initialization on the rendering
// context. 
void SetupRC()
    {
    int iSphere;
    
	// Calculate shadow matrix
    GLTVector3 vPoints[3] = {{ 0.0f, -0.4f, 0.0f },
                             { 10.0f, -0.4f, 0.0f },
                             { 5.0f, -0.4f, -5.0f }};
    
    // Grayish background
    glClearColor(fLowLight[0], fLowLight[1], fLowLight[2], fLowLight[3]);
         
    // Cull backs of polygons
    glCullFace(GL_BACK);
    glFrontFace(GL_CCW);
    glEnable(GL_CULL_FACE);
    glEnable(GL_DEPTH_TEST);
    
    // Setup light parameters
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, fNoLight);
    glLightfv(GL_LIGHT0, GL_AMBIENT, fLowLight);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, fBrightLight);
    glLightfv(GL_LIGHT0, GL_SPECULAR, fBrightLight);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    

    
     gltMakeShadowMatrix(vPoints, fLightPos, mShadowMatrix);
    
    // Mostly use material tracking
    glEnable(GL_COLOR_MATERIAL);
    glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
    glMateriali(GL_FRONT, GL_SHININESS, 128);
    
    gltInitFrame(&frameCamera);  // Initialize the camera
    
    // Randomly place the sphere inhabitants
    for(iSphere = 0; iSphere < NUM_SPHERES; iSphere++)
        {
        gltInitFrame(&spheres[iSphere]);    // Initialize the frame
        
        // Pick a random location between -20 and 20 at .1 increments
        spheres[iSphere].vLocation[0] = (float)((rand() % 400) - 200) * 0.1f;
        spheres[iSphere].vLocation[1] = 0.0f; 
        spheres[iSphere].vLocation[2] = (float)((rand() % 400) - 200) * 0.1f;
        }
    }


///////////////////////////////////////////////////////////
// Draw the ground as a series of triangle strips
void DrawGround(void)
    {
    GLfloat fExtent = 20.0f;
    GLfloat fStep = 1.0f;
    GLfloat y = -0.4f;
    GLint iStrip, iRun;
    
    for(iStrip = -fExtent; iStrip <= fExtent; iStrip += fStep)
        {
        glBegin(GL_TRIANGLE_STRIP);
            glNormal3f(0.0f, 1.0f, 0.0f);   // All Point up
            
            for(iRun = fExtent; iRun >= -fExtent; iRun -= fStep)
                {
                glVertex3f(iStrip, y, iRun);
                glVertex3f(iStrip + fStep, y, iRun);
                }
        glEnd();
        }
    }

///////////////////////////////////////////////////////////////////////
// Draw random inhabitants and the rotating torus/sphere duo
void DrawInhabitants(GLint nShadow)
    {
    static GLfloat yRot = 0.0f;         // Rotation angle for animation
    GLint i;

    if(nShadow == 0)
        yRot += 0.5f;
    else
        glColor3f(0.0f, 0.0f, 0.0f);
    
    // Draw the randomly located spheres
    if(nShadow == 0)
        glColor3f(0.0f, 1.0f, 0.0f);
        
    
    for(i = 0; i < NUM_SPHERES; i++)
        {
        glPushMatrix();
        gltApplyActorTransform(&spheres[i]);
        glutSolidSphere(0.3f, 17, 9);
        glPopMatrix();
        }

    glPushMatrix();
        glTranslatef(0.0f, 0.1f, -2.5f);
    
        if(nShadow == 0)
            glColor3f(0.0f, 0.0f, 1.0f);

        glPushMatrix();
            glRotatef(-yRot * 2.0f, 0.0f, 1.0f, 0.0f);
            glTranslatef(1.0f, 0.0f, 0.0f);
            glutSolidSphere(0.1f, 17, 9);
        glPopMatrix();
    
        if(nShadow == 0)
            {
            // Torus alone will be specular
            glColor3f(1.0f, 0.0f, 0.0f);
            glMaterialfv(GL_FRONT, GL_SPECULAR, fBrightLight);
            }
        
        glRotatef(yRot, 0.0f, 1.0f, 0.0f);
        gltDrawTorus(0.35, 0.15, 61, 37);
        glMaterialfv(GL_FRONT, GL_SPECULAR, fNoLight);
    glPopMatrix();
    }

        
// Called to draw scene
void RenderScene(void)
    {
    // Clear the window with current clearing color
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        
    glPushMatrix();
        gltApplyCameraTransform(&frameCamera);
        
        // Position light before any other transformations
        glLightfv(GL_LIGHT0, GL_POSITION, fLightPos);
        
        // Draw the ground
        glColor3f(0.60f, .40f, .10f);
        DrawGround();
        
        // Draw shadows first
        glDisable(GL_DEPTH_TEST);
        glDisable(GL_LIGHTING);
        glPushMatrix();
            glMultMatrixf(mShadowMatrix);
            DrawInhabitants(1);
        glPopMatrix();
        glEnable(GL_LIGHTING);
        glEnable(GL_DEPTH_TEST);
        
        // Draw inhabitants normally
        DrawInhabitants(0);

    glPopMatrix();
        
    // Do the buffer Swap
    glutSwapBuffers();
    glutPostRedisplay();
    }



// Respond to arrow keys by moving the camera frame of reference
void SpecialKeys(int key, int x, int y)
    {
    if(key == GLUT_KEY_UP)
        gltMoveFrameForward(&frameCamera, 0.1f);

    if(key == GLUT_KEY_DOWN)
        gltMoveFrameForward(&frameCamera, -0.1f);

    if(key == GLUT_KEY_LEFT)
        gltRotateFrameLocalY(&frameCamera, 0.1);
      
    if(key == GLUT_KEY_RIGHT)
        gltRotateFrameLocalY(&frameCamera, -0.1);
                        
    // Refresh the Window
    glutPostRedisplay();
    }


///////////////////////////////////////////////////////////
// Called by GLUT library when idle (window not being
// resized or moved)
void TimerFunction(int value)
    {
    // Redraw the scene with new coordinates
    glutPostRedisplay();
    glutTimerFunc(3,TimerFunction, 1);
    }

void ChangeSize(int w, int h)
    {
    GLfloat fAspect;

    // Prevent a divide by zero, when window is too short
    // (you cant make a window of zero width).
    if(h == 0)
        h = 1;

    glViewport(0, 0, w, h);
        
    fAspect = (GLfloat)w / (GLfloat)h;

    // Reset the coordinate system before modifying
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
	
    // Set the clipping volume
    gluPerspective(35.0f, fAspect, 1.0f, 50.0f);
        
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();    
    }

int main(int argc, char* argv[])
    {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(800,600);
    glutCreateWindow("OpenGL SphereWorld Demo + Lights and Shadow");
    glutReshapeFunc(ChangeSize);
    glutDisplayFunc(RenderScene);
    glutSpecialFunc(SpecialKeys);

    SetupRC();
    glutTimerFunc(33, TimerFunction, 1);

    glutMainLoop();

    return 0;
    }