cocos3.2版本 ，在 xxx::onDraw 直接调用 DrawPrimitives::drawLine
能成功画线，DrawPrimitives几个绘图函数也正常。
但如下使用更基本的opengl命令不行（看不到效果）：
glBegin(GL_TRIANGLES); // Drawing Using Triangles
glColor3f(1.0f,0.0f,0.0f); // Set The Color To Red
glVertex3f( 0.0f, 100.0f, 0.0f); // Top
glColor3f(0.0f,1.0f,0.0f); // Set The Color To Green
glVertex3f(-100.0f,-100.0f, 0.0f); // Bottom Left
glColor3f(0.0f,0.0f,1.0f); // Set The Color To Blue
glVertex3f( 100.0f,-100.0f, 0.0f); // Bottom Right
glEnd();
请问是什么原因