Question

openGL---旋转彩色三角形

#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glut.h>

int screenWidth = 800;
int screenHeight = 600;

float red = 1.0f;
float green = 1.0f;
float blue = 1.0f;

GLfloat rtri = 100.0f; // 用于三角形的角度
GLfloat rquad = -100.0f; // 用于四边形的角度

void myInit(void)
{
glShadeModel(GL_SMOOTH);
glClearColor(0.0,0.0,0.0,0.0);
glColor3f(red,green,blue);

glViewport(0,0,screenWidth,screenHeight);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

gluPerspective(45.0,(GLdouble)screenWidth/(GLdouble)screenHeight,0.1,100.0);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}

void myDisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();

glTranslatef(-1.5f,0.0f,-6.0f);

glRotatef(rquad,1.0f,0.0f,0.0f);
glBegin(GL_TRIANGLES); // 绘制三角形
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f); // 上顶点
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-1.0f,-1.0f, 0.0f); // 左下
glColor3f(0.0f,0.0f,1.0f);
glVertex3f( 1.0f,-1.0f, 0.0f); // 右下
glEnd();

glLoadIdentity();

glTranslatef(1.5f,0.0f,-6.0f);

glRotatef(rquad,1.0f,0.0f,0.0f);

glColor3f(0.5f,0.5f,1.0f);
glBegin(GL_QUADS); // 绘制正方形
glVertex3f(-1.0f, 1.0f, 0.0f); // 左上
glVertex3f( 1.0f, 1.0f, 0.0f); // 右上
glVertex3f( 1.0f,-1.0f, 0.0f); // 左下
glVertex3f(-1.0f,-1.0f, 0.0f); // 右下
glEnd();

rtri++;
rquad++;

glutSwapBuffers();
}

int main(int argc,char** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode( GLUT_DEPTH | GLUT_RGB | GLUT_DOUBLE);
glutInitWindowSize( screenWidth , screenHeight );
glutInitWindowPosition(100,100);
glutCreateWindow("Nehe");

myInit();
glutDisplayFunc(myDisplay);

glutMainLoop();
return 0;
}

为什么旋转不起，只有一张图。三角形并没有动。。。。。

请告诉我详细原因。

Answer 1

可以添加一个键盘操作，比如点一下a键调用一次glutPostRedisplay（重绘函数）。或者在glutSwapBuffers上做做手脚，这个算是绘制函数了，你可以在myDisplay里做个循环，把你绘制三角形和正方形的函数都放里面，还有glutSwapBuffers，每循环一次就rtri++; rquad++。但后者执行不太好，而且循环里建议加一个Sleep

Answer 2

当然不会动了……

glutDisplayFunc(myDisplay);

里的myDisplay只会调用一次啊～当然，如果窗口重绘的话它也会被再次调用～～～