opengl 画扇形

        glColor4f(0.0f, 0.0f, 0.0f, 0.35f);
        // 设置为Array
        glDisable(GL_TEXTURE_2D);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
        glDisableClientState(GL_COLOR_ARRAY);
        GLfloat *vertices = malloc(2 * sizeof(GLfloat) * (angle + 1));
        vertices[0] = 0;
        vertices[1] = 0; 
        for(int i = 0;i < angle; i++)
        {
            GLfloat x = r * cosf(CC_DEGREES_TO_RADIANS(i));
            GLfloat y = r * sinf(CC_DEGREES_TO_RADIANS(i));
            
            vertices[i * 2 + 2] = x;
            vertices[i * 2 + 2 + 1] = y;
        }
   
        
        glDisable(GL_TEXTURE_2D);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
        glDisableClientState(GL_COLOR_ARRAY);
        
        glVertexPointer(2, GL_FLOAT, 0, vertices);	
        glDrawArrays(GL_TRIANGLE_FAN, 0, (GLsizei)(angle + 2));
    
        // restore default state
        glEnableClientState(GL_COLOR_ARRAY);
        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glEnable(GL_TEXTURE_2D);
        free( vertices );