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glbeginner
02-11-2001, 05:54 PM
I am doing a simple OpenGL program but I am having problem in placing the light. Can anyone help me ? The following is my source code:


#include <math.h>
#include <gl\glut.h>
#include <gl\gl.h>
#include <gl\glu.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

float angle=0.0,deltaAngle = 0.0,ratio;
float x=0.0f,y=1.75f,z=5.0f;
float lx=0.0f,ly=0.0f,lz=-1.0f;
int deltaMove = 0,h=600,w=600, border=6;
int font=(int)GLUT_BITMAP_8_BY_13;
static GLint snowman_display_list;
int bitmapHeight=13;

int frame,time,timebase=0;
char s[30];

int mainWindow, subWindow1,subWindow2,subWindow3;

void initWindow();

void changeSize2(int w1, int h1)
{

// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
ratio = 1.0f * w1 / h1;
// Reset the coordinate system before modifying
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

// Set the viewport to be the entire window
glViewport(0, 0, w1, h1);

// Set the clipping volume
gluPerspective(45,ratio,0.1,1000);
glMatrixMode(GL_MODELVIEW);
}

void changeSize(int w1,int h1) {
if(h1 == 0)
h1 = 1;

w = w1;
h = h1;

glutSetWindow(subWindow1);
glutPositionWindow(border,border);
glutReshapeWindow(w-2*border, h/2 - border*3/2);
changeSize2(w-2*border, h/2 - border*3/2);

glutSetWindow(subWindow2);
glutPositionWindow(border,(h+border)/2);
glutReshapeWindow(w/2-border*3/2, h/2 - border*3/2);
changeSize2(w/2-border*3/2,h/2 - border*3/2);

glutSetWindow(subWindow3);
glutPositionWindow((w+border)/2,(h+border)/2);
glutReshapeWindow(w/2-border*3/2,h/2 - border*3/2);
changeSize2(w/2-border*3/2,h/2 - border*3/2);
}



void drawSnowMan() {


glColor3f(1.0f, 1.0f, 1.0f);

glutSolidTeapot(1);

}

GLuint createDL() {
GLuint snowManDL;

// Create the id for the list
snowManDL = glGenLists(2);

glNewList(snowManDL,GL_COMPILE);
drawSnowMan();
glEndList();
// start list

return(snowManDL);
}


void setOrthographicProjection() {

// switch to projection mode
glMatrixMode(GL_PROJECTION);
// save previous matrix which contains the
//settings for the perspective projection
glPushMatrix();
// reset matrix
glLoadIdentity();
// set a 2D orthographic projection
glOrtho(-300, 300, -300, 300, -300, 300);
// invert the y axis, down is positive
glScalef(1, -1, 1);
// mover the origin from the bottom left corner
// to the upper left corner
glTranslatef(x, y, z);
glMatrixMode(GL_MODELVIEW);
}

void resetPerspectiveProjection() {
// set the current matrix to GL_PROJECTION
glMatrixMode(GL_PROJECTION);
// restore previous settings
glPopMatrix();
// get back to GL_MODELVIEW matrix
glMatrixMode(GL_MODELVIEW);
}

void renderBitmapString(float x, float y, void *font,char *string)
{

char *c;
// set position to start drawing fonts
glRasterPos2f(x, y);
// loop all the characters in the string
for (c=string; *c != '\0'; c++) {
glutBitmapCharacter(font, *c);
}
}

void initScene() {

glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);

GLfloat light_ambient[] =
{0.0, 0.0, 0.0, 1.0};
GLfloat light_diffuse[] =
{1.0, 1.0, 1.0, 1.0};
GLfloat light_specular[] =
{1.0, 1.0, 1.0, 1.0};
GLfloat light_position[] =
{1.0, 1.0, 1.0, 0.0};

glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);

// Enable the light
glEnable(GL_LIGHT0);
glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
snowman_display_list = createDL();
}

void orientMe(float ang) {


lx = sin(ang);
lz = -cos(ang);
}


void moveMeFlat(int i) {
x = x + i*(lx)*0.1;
z = z + i*(lz)*0.1;
}


void renderScene2(int currentWindow) {


glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);




glPushMatrix();
glColor3f(1.0,0.0,0.0);
glTranslatef(x,y,z);
// glRotatef(170-angle*180.0/3.14,0.0,1.0,0.0);
glutSolidCone(0.2,0.8f,4,4);
glPopMatrix();

// Draw ground
/* glColor3f(0.9f, 0.9f, 0.9f);
glBegin(GL_QUADS);
glVertex3f(-100.0f, 0.0f, -100.0f);
glVertex3f(-100.0f, 0.0f, 100.0f);
glVertex3f( 100.0f, 0.0f, 100.0f);
glVertex3f( 100.0f, 0.0f, -100.0f);
glEnd();
*/
// Draw 36 SnowMen

glCallList(snowman_display_list);

if (currentWindow == subWindow1)
{
frame++;
time=glutGet(GLUT_ELAPSED_TIME);
if (time - timebase > 1000) {
sprintf(s,"FPS: %4.2f",frame*1000.0/(time-timebase));
timebase = time;
frame = 0;
}
glColor3f(0.0,1.0,1.0);
setOrthographicProjection();
glPushMatrix();
glLoadIdentity();
renderBitmapString(30,15,(void *)font,"GLUT Tutorial @ 3D Tech");
renderBitmapString(30,35,(void *)font,s);
renderBitmapString(30,55,(void *)font,"Esc - Quit");
glPopMatrix();
resetPerspectiveProjection();
}
glutSwapBuffers();
}

void renderScene() {
glutSetWindow(mainWindow);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glutSwapBuffers();
}

void renderScenesw1() {
glutSetWindow(subWindow1);
glLoadIdentity();
gluLookAt(x, y, z,
x + lx,y + ly,z + lz,
0.0f,1.0f,0.0f);

renderScene2(subWindow1);
}

void renderScenesw2() {
glutSetWindow(subWindow2);
glLoadIdentity();
gluLookAt(x, y+15, z,
x ,y - 1,z,
lx,0,lz);
renderScene2(subWindow2);
}

void renderScenesw3() {
glutSetWindow(subWindow3);
glLoadIdentity();
gluLookAt(x-lz*10 , y, z+lx*10,
x ,y ,z ,
0.0f,1.0f,0.0f);
renderScene2(subWindow3);
}

void renderSceneAll() {
if (deltaMove)
moveMeFlat(deltaMove);
if (deltaAngle) {
angle += deltaAngle;
orientMe(angle);
}
// renderScene();
renderScenesw1();
renderScenesw2();
renderScenesw3();
}

void processNormalKeys(unsigned char key, int x, int y) {

if (key == 27)
exit(0);
}

void pressKey(int key, int x, int y) {

switch (key) {
case GLUT_KEY_LEFT : deltaAngle = -0.01f;break;
case GLUT_KEY_RIGHT : deltaAngle = 0.01f;break;
case GLUT_KEY_UP : deltaMove = 1;break;
case GLUT_KEY_DOWN : deltaMove = -1;break;
}

}

void releaseKey(int key, int x, int y) {

switch (key) {
case GLUT_KEY_LEFT : if (deltaAngle < 0.0f)
deltaAngle = 0.0f;
break;
case GLUT_KEY_RIGHT : if (deltaAngle > 0.0f)
deltaAngle = 0.0f;
break;
case GLUT_KEY_UP : if (deltaMove > 0)
deltaMove = 0;
break;
case GLUT_KEY_DOWN : if (deltaMove < 0)
deltaMove = 0;
break;
}
}

int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(w,h);
mainWindow = glutCreateWindow("TESTING");
glutIgnoreKeyRepeat(1);
glutKeyboardFunc(processNormalKeys);
glutSpecialFunc(pressKey);
glutSpecialUpFunc(releaseKey);
glutReshapeFunc(changeSize);
glutDisplayFunc(renderScene);
glutIdleFunc(renderSceneAll);

subWindow1 = glutCreateSubWindow(mainWindow, border,border,w-2*border, h/2 - border*3/2);
glutDisplayFunc(renderScene);
initScene();

subWindow2 = glutCreateSubWindow(mainWindow, border,(h+border)/2,w/2-border*3/2, h/2 - border*3/2);
glutDisplayFunc(renderScenesw2);
initScene();

subWindow3 = glutCreateSubWindow(mainWindow, (w+border)/2,(h+border)/2,w/2-border*3/2,h/2 - border*3/2);
glutDisplayFunc(renderScenesw3);
initScene();

glutMainLoop();

return(0);
}