1、OpenGL 移動和旋轉的代碼：
移動代碼：glTranslatef(float a,float,b,float c);
如glTranslatef(1.5,1.5, 0);//移動旋轉中心的長度
旋轉代碼：glRotatef(float angle,float x,float y,float z);
如glRotatef(CurrentAngle, 0.0, 0.0, 1.0);
2、代碼演示
- 2.1 插入.cpp文件、.h頭文件
源文件和頭文件
- 2.2 在源文件中寫入代碼
#include <math.h>// For math routines (such as sqrt & trig)./<math.h>
#include <stdio.h>
#include <stdlib.h>// For the "exit" function/<stdlib.h>
#include
#include "SimpleAnim.h"
int RunMode = 1;// Used as a boolean (1 or 0) for "on" and "off"
// The next global variable controls the animation's state and speed.
float CurrentAngle = 0.0f;// Angle in degrees
float AnimateStep = 3.0f;// Rotation step per update
// These variables set the dimensions of the rectanglar region we wish to view.
const double Xmin = 0.0, Xmax = 3.0;
const double Ymin = 0.0, Ymax = 3.0;
// glutKeyboardFunc is called below to set this function to handle
//all "normal" key presses.
void myKeyboardFunc( unsigned char key, int x, int y )
{
switch ( key ) {
case 'r':
RunMode = 1-RunMode;// Toggle to opposite value
if ( RunMode==1 ) {
glutPostRedisplay();
}
break;
case 's':
RunMode = 1;
drawScene();
RunMode = 0;
break;
case 27:// Escape key
exit(1);
}
}
// glutSpecialFunc is called below to set this function to handle
//all "special" key presses. See glut.h for the names of
//special keys.
void mySpecialKeyFunc( int key, int x, int y )
{
switch ( key ) {
case GLUT_KEY_UP:
if ( AnimateStep < 1.0e3) {// Avoid overflow problems
AnimateStep *= sqrt(2.0);// Increase the angle increment
}
break;
case GLUT_KEY_DOWN:
if (AnimateStep>1.0e-6) {// Avoid underflow problems.
AnimateStep /= sqrt(2.0);// Decrease the angle increment
}
break;
}
}
/*
* drawScene() handles the animation and the redrawing of the
*graphics window contents.
*/
void drawScene(void)
{
// Clear the rendering window
glClearColor(0.0,0.0,0.0,0.0); //除顏色設為黑色
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //表示要清除顏色緩衝以及深度緩衝,實際完成了把整個窗口清除為黑色的任務
if (RunMode==1) {
// Calculate animation parameters
CurrentAngle += AnimateStep;
if ( CurrentAngle > 360.0 ) {
CurrentAngle -= 360.0*floor(CurrentAngle/360.0);// Don't allow overflow
}
}
// Rotate the image
glMatrixMode( GL_MODELVIEW );// Current matrix affects objects positions
glLoadIdentity();// Initialize to the identity
glTranslatef( 1.5, 1.5, 0.0 );// Translate rotation center from origin
glRotatef( CurrentAngle, 0.0, 0.0, 1.0 );// Rotate through animation angle
glTranslatef( -1.5, -1.5, 0.0 );// Translate rotation center to origin
// Draw three overlapping triangles of different colors
glBegin( GL_TRIANGLES );
glColor3f( 1.0, 0.0, 0.0 );
glVertex3f( 0.3, 1.0, 0.5 );
glVertex3f( 2.7, 0.85, 0.0 );
glVertex3f( 2.7, 1.15, 0.0 );
glColor3f( 0.0, 1.0, 0.0 );
glVertex3f(2.53, 0.71, 0.5 );
glVertex3f(1.46, 2.86, 0.0 );
glVertex3f(1.2, 2.71, 0.0 );
glColor3f( 0.0, 0.0, 1.0 );
glVertex3f(1.667, 2.79, 0.5);
glVertex3f(0.337, 0.786, 0.0);
glVertex3f(0.597, 0.636, 0.0);
glEnd();
// Flush the pipeline, swap the buffers
glFlush();
glutSwapBuffers();
if ( RunMode==1 )
{
glutPostRedisplay();// Trigger an automatic redraw for animation
}
}
// Initialize OpenGL's rendering modes
void initRendering()
{
glShadeModel( GL_FLAT );// The default value of GL_SMOOTH is usually better
glEnable( GL_DEPTH_TEST );// Depth testing must be turned on
}
// Called when the window is resized 當窗口最大化或者變成默認尺寸後
//w, h - width and height of the window in pixels.
void resizeWindow(int w, int h)
{
double scale, center;
double windowXmin, windowXmax, windowYmin, windowYmax;
// Define the portion of the window used for OpenGL rendering.
glViewport( 0, 0, w, h );// View port uses whole window
// Set up the projection view matrix: orthographic projection
// Determine the min and max values for x and y that should appear in the window.
// The complication is that the aspect ratio of the window may not match the
//aspect ratio of the scene we want to view.
w = (w==0) ? 1 : w;
h = (h==0) ? 1 : h;
if ( (Xmax-Xmin)/w < (Ymax-Ymin)/h ) {
scale = ((Ymax-Ymin)/h)/((Xmax-Xmin)/w);
center = (Xmax+Xmin)/2;
windowXmin = center - (center-Xmin)*scale;
windowXmax = center + (Xmax-center)*scale;
windowYmin = Ymin;
windowYmax = Ymax;
}
else {
scale = ((Xmax-Xmin)/w)/((Ymax-Ymin)/h);
center = (Ymax+Ymin)/2;
windowYmin = center - (center-Ymin)*scale;
windowYmax = center + (Ymax-center)*scale;
windowXmin = Xmin;
windowXmax = Xmax;
}
// Now that we know the max & min values for x & y
//that should be visible in the window,
//we set up the orthographic projection.
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( windowXmin, windowXmax, windowYmin, windowYmax, -1, 1 );
}
// Main routine
// Set up OpenGL, define the callbacks and start the main loop
int main( int argc, char** argv )
{
glutInit(&argc,argv);
// We're going to animate it, so double buffer
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH );
// Window position (from top corner), and size (width% and hieght)
glutInitWindowPosition( 10, 60 );
glutInitWindowSize( 360, 360 );
glutCreateWindow( "SimpleAnim" );
// Initialize OpenGL as we like it..
initRendering();
// Set up callback functions for key presses
glutKeyboardFunc( myKeyboardFunc );// Handles "normal" ascii symbols
glutSpecialFunc( mySpecialKeyFunc );// Handles "special" keyboard keys
// Set up the callback function for resizing windows
glutReshapeFunc( resizeWindow );
// Call this for background processing
// glutIdleFunc( myIdleFunction );
// call this whenever window needs redrawing
glutDisplayFunc( drawScene );
fprintf(stdout, "Arrow keys control speed. Press \"r\" to run, \"s\" to single step.\\n");
// Start the main loop. glutMainLoop never returns.
glutMainLoop( );
return(0);// This line is never reached.
}
- 2.3 在頭文件中寫入代碼
// .cpp用到的函數
void myKeyboardFunc(unsigned char key, int x, int y);
void mySpecialKeyFunc(int key, int x, int y);
void drawScene(void);
void initRendering();
void resizeWindow(int w, int h);
3、運行代碼
4、代碼功能
（1）按下鍵盤上的"r"可停止或者恢復三角形旋轉
（2）按下鍵盤上的"s"單步運行旋轉。
通過這個案例學習了C++的基本編程方法、學習Opengl的移動、旋轉命令。
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