I have been at this project for weeks…and it finally works!! yay!!! But now I have a new problem…I want to be able to just show the X and Y axis throughout my entire animation. I have tried plugging in this code snippet but I can’t figure out where the correct placement would be. I have tried pushing and popping, and putting it in different locations within my display function, but I have yet to see any lines drawn…any suggestions?
Code Snippet:
glColor3f(1.0, 1.0, 1.0);
glBegin(GL_LINE);
glVertex2f(400, 0);
glVertex2f(400, 800);
glEnd();
glBegin(GL_LINE);
glVertex2f(0, 400);
glVertex2f(800, 400);
glEnd();
And here is my amazing program in all of it’s glory! It’ s a very simple animation showing how rotation is done in openGL.
#include <stdlib.h>
#include <stdio.h>
#include <GLUT/glut.h>
float yPosition = 0;
float zPosition = 0;
float topLeftX = 0.5;
float topLeftY = 0.75;
float topRightX = 0.75;
float topRightY = 0.75;
float bottomRightX = 0.75;
float bottomRightY = 0.5;
float bottomLeftX = 0.5;
float bottomLeftY = 0.5;
float xPos = 0.75;
float yPos = 0.75;
float zPos = 0;
float startXPos = 0.75;
float startYPos = 0.75;
int yDirection = 0; //1-up, 0-down
int xDirection = 0; //1-stopped, 0-left, 2- right
int yRotate = 0; //0- rotate, 1- stop rotating
int zRotate = 0; //0- rotate, 1- stop rotating
int count;
//the init function is used to initialize things that only need to be execute once
void init()
{
glClearColor(1.0,1.0,1.0,0.0);
glEnable(GL_DEPTH_TEST);
}
void setWindow(double left, double right, double bottom, double top)
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
}
void setViewport(int left, int right, int bottom, int top)
{
glViewport(left, bottom, right-left, top-bottom);
}
//function for drawing, called whenever there needs to be a redraw
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(1,0,0);
glPushMatrix();
glTranslated(xPos, yPos, 0);
glRotatef(yPosition, 0, 1, 0);
glRotatef(zPosition, 0, 0, 1);
if (xDirection==0){ //if moving left
xPos-=0.0005; //move in a negative direction along the xaxis
yPos = (startYPos*xPos/startXPos);
glutPostRedisplay();
}
if (xDirection==1) {
xPos==0.0;
yPos==0.0;
yPosition+=0.05;
zPosition+=0.05;
glutPostRedisplay();
}
if (xDirection==2){
xPos+=0.0005; //move in a negative direction along the xaxis
yPos = (startYPos*xPos/startXPos);
glutPostRedisplay();
}
if (xDirection==3) {
xPos==0.0;
yPos==0.0;
glutPostRedisplay();
}
if (xDirection==0 && xPos > 0.0) {
xDirection=0;
}
if (xDirection==0 && xPos < 0.0) {
xDirection=1; //stop at origin
}
if (xDirection==1 && yPosition > 45.0) {
xDirection=2;
}
if (xDirection==2 && xPos==startXPos) {
xDirection=3;
}
//glutWireCube(.25);
glBegin(GL_POLYGON);
glVertex2f(-0.1, -0.1); //bottom left
glVertex2f(-0.1,0.1); //top left
glVertex2f(0.1, 0.1); //top right
glVertex2f(0.1, -0.1); //bottom right
glEnd();
glPopMatrix();
glutSwapBuffers();
}
void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, (GLfloat) w/ (GLfloat) h, 1.0, 20.0);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}
void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
case 'y':
yPosition=yPosition+5;
if (yPosition>360)
yPosition=0;
glutPostRedisplay();
break;
case 'z':
zPosition=zPosition+5;
if (zPosition>360)
zPosition=0;
glutPostRedisplay();
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE); //double pixel buffer that holds RGB
glutInitWindowSize(800, 800);
glutInitWindowPosition(0,0);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
//glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}