glRotatef example c c++ objc java

Name

glRotatef — multiply the current matrix by a rotation matrix

C Specification

`void glRotated(`	GLdouble	`angle`,
	GLdouble	`x`,
	GLdouble	`y`,
	GLdouble	`z)`;

`void glRotatef(`	GLfloat	`angle`,
	GLfloat	`x`,
	GLfloat	`y`,
	GLfloat	`z)`;

Parameters

angle: Specifies the angle of rotation, in degrees.
x, y, z: Specify the x, y, and z coordinates of a vector, respectively.

Description

glRotatef produces a rotation of angle degrees around the vector x y z . The current matrix (see glMatrixMode) is multiplied by a rotation matrix with the product replacing the current matrix, as if glMultMatrix were called with the following matrix as its argument:

x 2 ⁡ 1 - c + c x ⁢ y ⁡ 1 - c - z ⁢ s x ⁢ z ⁡ 1 - c + y ⁢ s 0 y ⁢ x ⁡ 1 - c + z ⁢ s y 2 ⁡ 1 - c + c y ⁢ z ⁡ 1 - c - x ⁢ s 0 x ⁢ z ⁡ 1 - c - y ⁢ s y ⁢ z ⁡ 1 - c + x ⁢ s z 2 ⁡ 1 - c + c 0 0 0 0 1

Where c = cos ⁡ angle , s = sin ⁡ angle , and x y z = 1 (if not, the GL will normalize this vector).
If the matrix mode is either GL_MODELVIEW or GL_PROJECTION, all objects drawn after glRotatef is called are rotated. Use glPushMatrix and glPopMatrix to save and restore the unrotated coordinate system.

Notes

This rotation follows the right-hand rule, so if the vector x y z points toward the user, the rotation will be counterclockwise.

Errors

GL_INVALID_OPERATION is generated if glRotate is executed between the execution of glBegin and the corresponding execution of glEnd.

Associated Gets

glGet with argument GL_MATRIX_MODE
glGet with argument GL_COLOR_MATRIX
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX

Copyright

Example of glRotatef

#include <GL/glut.h>    // includes gl.h glu.h
#include <iostream>
#include <windows.h>
#include <math.h>
void SetupRC();
void RenderScene(void);
void Keyboard (unsigned char key, int x, int y);
void ChangeSize(int w, int h);
float xRot =0.0f;
float yRot =0.0f;
float zRot =0.0f;

int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode( GLUT_SINGLE | GLUT_RGBA );
glutCreateWindow ("Cube Drawing");
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
glutKeyboardFunc(Keyboard);
SetupRC();
glutMainLoop();
return 0;
}
void SetupRC()
{

glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

glColor3f(0.0f, 1.0f, 0.0f);
//glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
}
void RenderScene(void)
{
glClear (GL_COLOR_BUFFER_BIT);
/*
glBegin(GL_POINTS);
//glVertex3i(0,0,0);
//glVertex3i(100,0,0);
glEnd();
*/
glPushMatrix ();
glRotatef(xRot, 1.0f, 0.0f, 0.0f);
glRotatef(yRot, 0.0f, 1.0f, 0.0f);
glRotatef(zRot, 0.0f, 0.0f, 1.0f);
// draw Cube
glutWireCube (50.0);
glPopMatrix ();
glFlush ();
}
void ChangeSize(int w, int h)
{
GLfloat nRange = 100.0f;
// h가 0일 때
if(h == 0)
  h = 1;

glViewport(0, 0, w, h);

glMatrixMode (GL_PROJECTION);
//gluLookAt (0.0, 0.0, 0.0, 0.0, 0.0, -100.0, 0.0, 1.0, 0.0);
gluPerspective (0.0, w/h, 0.0, 100.0);

glLoadIdentity();

if (w <= h)
  glOrtho
  (-nRange, nRange,
  -nRange*h/w, nRange*h/w,
  -nRange, nRange);
else
  glOrtho
  (-nRange*w/h, nRange*w/h,
  - nRange, nRange,
  -nRange, nRange);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void Keyboard (unsigned char key, int x, int y)
{
if(key == 'x'){
  xRot+=0.5;
  glutPostRedisplay();
}
if(key == 'y'){
  yRot+=0.5;
  glutPostRedisplay();
}
if(key == 'z'){
   zRot+=0.5;
  glutPostRedisplay();
}
}

Example source code bank

Thursday, June 2, 2011