PDA

View Full Version : Help needed regarding GLOrtho



src
02-12-2002, 05:10 PM
Hi,
I'm using the following code to toggle b/n
Ortho and Perspective.
But it doesn't toggle properly (toggles only first time).
Also, the image is inverted when I use
glOrtho
Please help me modify code. The code is given below:
#include "glut.h"
#include <math.h>
#include "gl\gl.h"
#include "gl\glu.h"
#include <iostream.h>
#include <stdlib.h>
static GLdouble ortho_left = -5;
static GLdouble ortho_right = 5;
static GLdouble ortho_bottom = -5;
static GLdouble ortho_top = 5;
static GLdouble ortho_near = 1;
static GLdouble ortho_far = 30;

static float angle=0.0,ratio;
static float x=0.0f,y=1.75f,z=5.0f;
static float lx=0.0f,ly=0.0f,lz=-1.0f;
static GLint snowman_display_list;

static int k=0;

void renderScene(void);

void changeSize(int w, int h)
{

if(k==0)
{
if(h == 0)
h = 1;
ratio = 1.0f * w / h;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, w, h);
gluPerspective(45,ratio,1,1000);
renderScene();
glutPostRedisplay();
}
else
{
if(h == 0)
h = 1;
ratio = 1.0f * w / h;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, w, h);
//glOrtho(-200.0,200.0,-200.0,200.0,10.0,250.0);
if (w>h) glOrtho(ortho_left*w/h,ortho_right *w/h,ortho_top,ortho_bottom,ortho_near,ortho_far);
else glOrtho(ortho_left,ortho_right,ortho_top*h/w,ortho_bottom*h/w,ortho_near,ortho_far);
renderScene();
glutPostRedisplay();
}

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(x, y, z,x + lx,y + ly,z + lz,0.0f,1.0f,0.0f);

glutPostRedisplay();

}


void drawSnowMan() {

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

// Body
glTranslatef(0.0f ,0.75f, 0.0f);
glutSolidSphere(0.75f,20,20);


// Head
glTranslatef(0.0f, 1.0f, 0.0f);
glutSolidSphere(0.25f,20,20);

// Eyes
glPushMatrix();
glColor3f(0.0f,0.0f,0.0f);
glTranslatef(0.05f, 0.10f, 0.18f);
glutSolidSphere(0.05f,10,10);
glTranslatef(-0.1f, 0.0f, 0.0f);
glutSolidSphere(0.05f,10,10);
glPopMatrix();

// Nose
glColor3f(1.0f, 0.5f , 0.5f);
glRotatef(0.0f,1.0f, 0.0f, 0.0f);
glutSolidCone(0.08f,0.5f,10,2);
}

GLuint createDL()
{
GLuint snowManDL;
snowManDL = glGenLists(1);
glNewList(snowManDL,GL_COMPILE);
drawSnowMan();
glEndList();
return(snowManDL);
}

void initScene()
{

glEnable(GL_DEPTH_TEST);
snowman_display_list = createDL();

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

// Draw ground

glColor3f(0.6f, 0.6f, 0.6f);
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 4 SnowMen

for(int i = 0; i < 2; i++)
for(int j=0; j < 2; j++) {
glPushMatrix();
glTranslatef(i*10.0,0,j * 10.0);
glCallList(snowman_display_list);;
glPopMatrix();
}

glutSwapBuffers();
}

void orientMe(float ang) {


lx = sin(ang);
lz = -cos(ang);
glLoadIdentity();
gluLookAt(x, y, z,x + lx,y + ly,z + lz,0.0f,1.0f,0.0f);
}


void moveMeFlat(int i)
{
x = x + i*(lx)*0.1;
z = z + i*(lz)*0.1;
glLoadIdentity();
gluLookAt(x, y, z, x + lx,y + ly,z + lz, 0.0f,1.0f,1.0f);
}
void moveMeFlat1(int i)
{
x = x ;
z = z ;
glLoadIdentity();
gluLookAt(x, y, z,x + lx,y + ly,z + lz,0.0f,0.0f,0.0f);
}
void processNormalKeys(unsigned char key, int x, int y) {

if (key == 27)
exit(0);
switch(key)
{
case 'p': if (k==0) {k=1;}
else if (k==1) {k=0;}

if (k==0)
{
cout<<"persp"<<endl;
gluPerspective(45,1.0f *(640/360),1,1000);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(x, y, z,x + lx,y + ly,z + lz,0.0f,1.0f,0.0f);
glEnable(GL_DEPTH_TEST);
renderScene();
glutPostRedisplay();
}
else
{
glEnable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(ortho_left,ortho_right,ortho_top,ortho_bot tom,ortho_near,ortho_far);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(x, y, z,x + lx,y + ly,z + lz,1.0f,1.0f,0.0f);
cout<<"ortho"<<endl;
renderScene();
glutPostRedisplay();
}
glutPostRedisplay();


break;
}
}

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

switch (key) {
case GLUT_KEY_LEFT :
if(k==0)
{
angle -= 0.01f;orientMe(angle);
}
else
{
angle -= 0.01f;orientMe(angle);
}
break;
case GLUT_KEY_RIGHT :
if(k==0)
{
angle += 0.01f;orientMe(angle);
}
else
{
angle += 0.01f;orientMe(angle);
}
break;
break;
case GLUT_KEY_UP :
if (k==0){
moveMeFlat(1);} else {moveMeFlat1(1);}break;
case GLUT_KEY_DOWN :
if (k==0){
moveMeFlat(-1);} else {moveMeFlat1(-1);} break;
}
}
int main(int argc, char **argv)
{

glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(640,360);
glutCreateWindow("");
initScene();
glutKeyboardFunc(processNormalKeys);
glutSpecialFunc(inputKey);
glutDisplayFunc(renderScene);
glutIdleFunc(renderScene);
glutReshapeFunc(changeSize);
glutMainLoop();
return(0);
}

Bob
02-13-2002, 12:36 AM
The call to glOrtho should probably be



glOrtho(ortho_left,ortho_right,ortho_bottom,ortho_ top,ortho_near,ortho_far);

Note that the third and fourth parameters are changed. They define the bottom and the top coordinates, nor top and bottom.