OpenGL入门笔记（四）

前面一直在画二维图形，其实三维图形的绘制就是以其为基础，可以说二维不过是三维的一种特例（相当与Z=0）。比如说要画一个正方体，它有上下左右前后共六个面组成，也就是要画出六个正方形就可以了，只是要注意绘制时应该按逆时针绘制（好像是进行纹理映射时需要的。。。）

我们必须将OpenGL屏幕想象成一张很大的画纸，后面还带着许多透明的层。差不多就是个由大量的点组成的立方体。这些点从左至右、从上至下、从前到后的布满了这个立方体。如果能想象的出在屏幕的深度方向，就应该在设计新3D对象时没有任何问题。


int DrawGLScene(GLvoid)






{


glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


glLoadIdentity();


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


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


glBegin(GL_TRIANGLES);


glColor3f(1.0f,0.0f,0.0f);


glVertex3f( 0.0f, 1.0f, 0.0f);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f(-1.0f,-1.0f, 1.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f( 1.0f,-1.0f, 1.0f);




glColor3f(1.0f,0.0f,0.0f);


glVertex3f( 0.0f, 1.0f, 0.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f( 1.0f,-1.0f, 1.0f);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f( 1.0f,-1.0f, -1.0f);




glColor3f(1.0f,0.0f,0.0f);


glVertex3f( 0.0f, 1.0f, 0.0f);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f( 1.0f,-1.0f, -1.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f(-1.0f,-1.0f, -1.0f);




glColor3f(1.0f,0.0f,0.0f);


glVertex3f( 0.0f, 1.0f, 0.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f(-1.0f,-1.0f,-1.0f);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f(-1.0f,-1.0f, 1.0f);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f(-1.0f,-1.0f,1.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f(1.0f,-1.0f,1.0f);


glColor3f(0.0,1.0f,0.0f);


glVertex3f(1.0f,-1.0f,-1.0f);


glColor3f(0.0f,0.0f,1.0f);


glVertex3f(-1.0f,-1.0f,-1.0f);


glEnd();




glLoadIdentity();


glTranslatef(1.5f,0.0f,-7.0f);


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


glBegin(GL_QUADS);


glColor3f(0.0f,1.0f,0.0f);


glVertex3f( 1.0f, 1.0f,-1.0f);


glVertex3f(-1.0f, 1.0f,-1.0f);


glVertex3f(-1.0f, 1.0f, 1.0f);


glVertex3f( 1.0f, 1.0f, 1.0f);




glColor3f(1.0f,0.5f,0.0f);


glVertex3f( 1.0f,-1.0f, 1.0f);


glVertex3f(-1.0f,-1.0f, 1.0f);


glVertex3f(-1.0f,-1.0f,-1.0f);


glVertex3f( 1.0f,-1.0f,-1.0f);




glColor3f(1.0f,0.0f,0.0f);


glVertex3f( 1.0f, 1.0f, 1.0f);


glVertex3f(-1.0f, 1.0f, 1.0f);


glVertex3f(-1.0f,-1.0f, 1.0f);


glVertex3f( 1.0f,-1.0f, 1.0f);


glColor3f(1.0f,1.0f,0.0f);


glVertex3f( 1.0f,-1.0f,-1.0f);


glVertex3f(-1.0f,-1.0f,-1.0f);


glVertex3f(-1.0f, 1.0f,-1.0f);


glVertex3f( 1.0f, 1.0f,-1.0f);




glColor3f(0.0f,0.0f,1.0f);


glVertex3f(-1.0f, 1.0f, 1.0f);


glVertex3f(-1.0f, 1.0f,-1.0f);


glVertex3f(-1.0f,-1.0f,-1.0f);


glVertex3f(-1.0f,-1.0f, 1.0f);




glColor3f(1.0f,0.0f,1.0f);


glVertex3f( 1.0f, 1.0f,-1.0f);


glVertex3f( 1.0f, 1.0f, 1.0f);


glVertex3f( 1.0f,-1.0f, 1.0f);


glVertex3f( 1.0f,-1.0f,-1.0f);


glEnd();




rtri+=0.2f;


rquad-=0.15f;


return TRUE;


}