Advanced OpenGL++ base

base.adv.gl.cpp

// g++ src.cpp -­lglut ­-lGL ­-lGLU; ./a.out
#include <iostream>
#include <cmath>
#include <GL/glut.h>
#include <GL/glu.h>
#include <GL/gl.h>

// CAMERA position
GLfloat CAMERA_X = 0;
GLfloat CAMERA_Y = 0;
GLfloat CAMERA_Z = 10;
GLfloat CAMERA_RX = 0;
GLfloat CAMERA_RY = 0;
GLfloat CAMERA_RZ = 0;

// MOUSE location
GLfloat MOUSE_X = 0;
GLfloat MOUSE_Y = 0;

// PERSPECTIVE vars
GLfloat PERSP_ANGLE = 20;
GLfloat PERSP_MINDIST = 0.1f;
GLfloat PERSP_MAXDIST = 1000.0f;

GLfloat light0_position[] = { 0,0,1, 0 };

void drawScene()
{
    glColor3f(1,0,0);
    glutSolidTeapot(1);
}

void idleFunc()
{
    // glutPostRedisplay();
}

void renderScene()
{
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    gluLookAt(CAMERA_X,CAMERA_Y,CAMERA_Z, 0,0,0, 0,1,0);

    glRotatef(CAMERA_RX, 1,0,0);
    glRotatef(CAMERA_RY, 0,1,0);
    glRotatef(CAMERA_RZ, 0,0,1);
    glLightfv(GL_LIGHT0, GL_POSITION, light0_position);

    drawScene();

    glutSwapBuffers();
}

void passiveMotionHandler(int x, int y)
{
    MOUSE_X = x;
    MOUSE_Y = y;
}

void motionHandler(int x, int y)
{
    glutPostRedisplay();
}

void pickedHandler(GLint hits, GLuint buffer[])
{
    // hits is the number of hits, buffer[ (N*4)-1 ] are the IDs picked
    glutPostRedisplay();
}

void pickingFunction(int x, int y)
{
    GLuint buff[64] = {0};
    GLint hits, view[4];

    glSelectBuffer(64, buff);
    glGetIntegerv(GL_VIEWPORT, view);
    glRenderMode(GL_SELECT);
    glInitNames();
    glPushName(0);

    glMatrixMode(GL_PROJECTION);
        glPushMatrix();
        glLoadIdentity();
        gluPickMatrix(x, y, 1.0, 1.0, view);
        gluPerspective(PERSP_ANGLE, view[2]*1.0f/view[3], PERSP_MINDIST, PERSP_MAXDIST);
    glMatrixMode(GL_MODELVIEW);

    glutSwapBuffers();
    renderScene();

    glMatrixMode(GL_PROJECTION);
        glPopMatrix();
        hits = glRenderMode(GL_RENDER);
        if (hits>0) pickedHandler(hits, buff);
    glMatrixMode(GL_MODELVIEW);
}

void mouseHandler(int button, int state, int x, int y)
{
    if  (button==GLUT_LEFT_BUTTON && state==GLUT_DOWN) pickingFunction(x, y);
}

void keysHandler(unsigned char k, int x, int y)
{
    glutPostRedisplay();
}

void specialKeysHandler(int k, int x, int y)
{
    glutPostRedisplay();
    if (k==GLUT_KEY_LEFT) CAMERA_RY += 1;
    else if (k==GLUT_KEY_RIGHT) CAMERA_RY -= 1;
    else if (k==GLUT_KEY_UP) CAMERA_RX += 1;
    else if (k==GLUT_KEY_DOWN) CAMERA_RX -= 1;
}


void reshapeScene(int w, int h)
{
    glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glViewport(0, 0, w, h);
        gluPerspective(PERSP_ANGLE, w*1.0f/h, PERSP_MINDIST, PERSP_MAXDIST);
    glMatrixMode(GL_MODELVIEW);
}

void initDisplayLists()
{
    /* init display lists here, call with glCallList(N);
    glNewList(N, GL_COMPILE);
    ...
    glEndList();
    */
}

void initLights()
{
    // Lights
    glEnable(GL_LIGHTING);
    float ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f };
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientLight);
    glEnable(GL_LIGHT0);
    GLfloat light0_ambientLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };
    GLfloat light0_diffuseLight[] = { 0.5f, 0.5f, 0.2f, 1.0f };
    GLfloat light0_specularLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };
    glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambientLight);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuseLight);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specularLight);
    glLightfv(GL_LIGHT0, GL_POSITION, light0_position);

    // Materials
    glEnable(GL_COLOR_MATERIAL);
    glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
    float specReflection[] = { 1,1,1,1 };
    glMaterialfv(GL_FRONT, GL_SPECULAR, specReflection);
    glMateriali(GL_FRONT, GL_SHININESS, 40);

    // Fog
    // glEnable(GL_FOG);
    glFogi(GL_FOG_MODE, GL_EXP2);
    GLfloat fog[] = { 1,1,1, 1 };
    glFogfv(GL_FOG_COLOR, fog);
    glFogf(GL_FOG_DENSITY, 0.05f);
}

void init()
{
    glEnable(GL_DEPTH_TEST);

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

    //glEnable(GL_NORMALIZE);
    //glEnable(GL_CULL_FACE);

    initDisplayLists();
    initLights();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB|GLUT_DEPTH|GLUT_DOUBLE);
    glutInitWindowSize(1000, 600);
    glutCreateWindow("Base | OpenGL");

    glutDisplayFunc(renderScene);
    glutReshapeFunc(reshapeScene);

    glutMouseFunc(mouseHandler);
    glutMotionFunc(motionHandler);
    glutPassiveMotionFunc(passiveMotionHandler);
    glutKeyboardFunc(keysHandler);
    glutSpecialFunc(specialKeysHandler);
    glutIdleFunc(idleFunc);

    init();

    glutMainLoop();
}