OpenGL 2D rotation problem
In the following program i am trying to draw a simple house. The coordinates are defined in the house array. I need to rotate the house and display both rotated as well as the original house. But why is the rotated house not being displayed?
//Program to create a house like figure and rotate ir about a given fixed point using OpenGL functions.
#include <glut.h>
#include <stdio.h>
float house [11][2] = {{100,200},{200,250},{300,200},{100,200},{100,100},{175,100},{175,150},{225,150},{225,100},{300,100},{300,200}};
void init()
{
glClearColor(1,1,1,0);
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0,800,0,800);
glMatrixMode(GL_MODELVIEW);
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
//NORMAL HOUSE
glColor3f(1,0,0);
glBegin(GL_LINE_LOOP);
for(int i=0;i<11;i++)
glVertex2fv(house[i]);
glEnd();
glFlush();
//ROTATED HOUSE
glPushMatrix()开发者_C百科;
glRotatef(60,0,1,0);
glColor3f(1,1,0);
glBegin(GL_LINE_LOOP);
for(int i=0;i<11;i++)
glVertex2fv(house[i]);
glEnd();
glFlush();
glPopMatrix();
}
void main(int argc,char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(800,800);
glutInitWindowPosition(100,100);
glutCreateWindow("House rotation");
init();
glutDisplayFunc(display);
glutMainLoop();
}
Try rotating on the Z axis instead of the Y axis:
//Program to create a house like figure and rotate ir about a given fixed point using OpenGL functions.
#include <GL/glut.h>
float house [11][2] = {{100,200},{200,250},{300,200},{100,200},{100,100},{175,100},{175,150},{225,150},{225,100},{300,100},{300,200}};
void display()
{
glClearColor(1,1,1,0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0,800,0,800);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
//NORMAL HOUSE
glColor3f(1,0,0);
glBegin(GL_LINE_LOOP);
for(int i=0;i<11;i++)
glVertex2fv(house[i]);
glEnd();
//ROTATED HOUSE
glPushMatrix();
glTranslatef(100,100,0);
glRotatef(60,0,0,1);
glTranslatef(-100,-100,0);
glColor3f(1,1,0);
glBegin(GL_LINE_LOOP);
for(int i=0;i<11;i++)
glVertex2fv(house[i]);
glEnd();
glPopMatrix();
}
void main(int argc,char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(800,800);
glutInitWindowPosition(100,100);
glutCreateWindow("House rotation");
glutDisplayFunc(display);
glutMainLoop();
}
EDIT: This one should rotate around the bottom corner.
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