openGL的问题，关于三角形旋转的。。新手入门

[ztdtc]

老师要求我们进行4个三角型的旋转，请大家帮忙看看我的程序里有什么错误，为什么不会进行旋转？谢谢了

#include<GL/glut.h>
#include<math.h>

double temp;

#define DEG_TO_RAD 0.017453
GLfloat theta = 1.0;

void myidle()
{
theta += 0.9;
if (theta >= 360.0)
theta -= 360.0;
theta = theta* DEG_TO_RAD;

glutPostRedisplay();
}


class wcPt2D
{
public:
GLfloat x,y;
};

void init (void)
{
glClearColor (1.0,1.0,1.0,0.0);
glMatrixMode (GL_PROJECTION);
gluOrtho2D (-100.0,100.0,-100.0,100.0);
glMatrixMode (GL_MODELVIEW);
}

void triangle (wcPt2D *verts)
{
GLint k;
GLfloat i,j;

for(k=0;k<=2;k++)
{
i=verts[k].x;
j=verts[k].y;
verts[k].x=i*cos(theta)-j*sin(theta);
verts[k].y=i*sin(theta)+j*cos(theta);
}


glBegin (GL_TRIANGLES);
for (k=0;k<3;k++)
glVertex2f (verts[k].x,verts[k].y);
glEnd();
}

void displayFcn (void)
{
wcPt2D verts [3] ={{-50.0,-25.0},{50.0,-25.0},{0.0,50.0}};

glClear (GL_COLOR_BUFFER_BIT);
glColor3f (0.0,0.0,1.0);
glViewport (0,0,300,300);
triangle (verts);



glColor3f (1.0,1.0,0.0);
glViewport (300,0,300,300);
triangle (verts);



glColor3f (1.0,0.0,1.0);
glViewport (300,300,300,300);
triangle (verts);



glColor3f (1.0,0.0,0.0);
glViewport (0,300,300,300);
triangle (verts);

glEnd();
glFlush();
glutSwapBuffers();


}
void main (int argc, char ** argv)
{

glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
glutInitWindowPosition (50,50);
glutInitWindowSize(600,600);
glutCreateWindow("Split-Screen Example");

init ();

glutDisplayFunc (displayFcn);

glutIdleFunc(myidle);

glutMainLoop();
}

[猪的飞想]

哪个是你画图的啊？有更新吗？
你的用glRotatef();和glTranslatef();控制一下！

[xiekun2008]

建议你看看NeHe的OpenGL教程。
上边有个旋转金字塔的例子，网上很好找的。

[量子高宏亮]

void myidle()
{
theta += 0.9;
if (theta >= 360.0)
theta -= 360.0;
theta = theta* DEG_TO_RAD; //这个地方的有问题，theta变量一会表示角度，一会又表示弧度，分两个变量表示就好了
//theta_RAD = theta* DEG_TO_RAD;

glutPostRedisplay();
}