OpenGL学习十一：抗锯齿

启用抗锯齿 还是以glEnable来启用抗锯齿,可以根据不同图形进行处理 1. GL_POINT_SMOOTH 点 2. GL_LINE_SMOOTH 线 3. GL_POLYGON_SMOOTH 多边形 抗锯齿质量 效果越好，那么计算机速度就越慢 glHint用于对点，线，多边形的抗锯齿程度进行设置 1. GL_DONT_CARE 放弃，应该是系统默认吧 2. GL_FASTEST 速度优先 3. GL_NICEST 图形显示质量优先

点抗锯齿（RGBA模式） glPointSize(10); glEnable (GL_POINT_SMOOTH);//启动点抗锯齿 glHint (GL_POINT_SMOOTH, GL_NICEST); //图像渲染质量 左图1：不启动抗锯齿 右图2：启动抗锯齿

线抗锯齿 glEnable (GL_BLEND); glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glEnable (GL_LINE_SMOOTH); glHint (GL_LINE_SMOOTH, GL_NICEST); glLineWidth (10); 右图1：不启动抗锯齿 右图2：启动抗锯齿，不启用混合 右图2：启动抗锯齿，启用混合    多重采样 多重采样的技巧使用额外的颜色，深度和模板信息，对OPENGL图元进行抗锯齿处理 1.创建一个多重采样的窗口    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_MULTISAMPLE); 2.查询状态变量GL_SAMPLE_BUFFERS    glGetIntegerv (GL_SAMPLE_BUFFERS, buf); 3.查询状态变量GL_SAMPLE   glGetIntegerv (GL_SAMPLES, sbuf); 如果buf=1 sbuf>1 就可以使用多重采样 4.启动多重采样 glEnable(GLUT_MULTISAMPLE) 说明：多边形抗锯齿做好采用多重采样进行抗锯齿   #include "header.h" static float rotAngle = 0.; void init(void) { GLfloat values[2]; glGetFloatv (GL_LINE_WIDTH_GRANULARITY, values); printf ("GL_LINE_WIDTH_GRANULARITY value is %3.1f\n", values[0]); glGetFloatv (GL_LINE_WIDTH_RANGE, values); printf ("GL_LINE_WIDTH_RANGE values are %3.1f %3.1f\n", values[0], values[1]); glEnable (GL_LINE_SMOOTH); glEnable (GL_BLEND); glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE); glLineWidth (1.5); glEnable (GL_POINT_SMOOTH); glHint (GL_POINT_SMOOTH_HINT, GL_NICEST); glPointSize(100); glClearColor(0.0, 0.0, 0.0, 0.0); } void display(void) { glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0,600,0,600,-10,10); glColor3f (1.0, 1.0, 1.0); glBegin (GL_LINES); glVertex2f (0, 300); glVertex2f (600, 300); glEnd (); glBegin (GL_LINES); glVertex2f (300, 600); glVertex2f (300, 0); glEnd (); glPopMatrix(); glEnable (GL_LINE_SMOOTH); glEnable (GL_BLEND); glPushMatrix(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-150,450,-450,150,-10,10); glPushMatrix(); glRotatef(rotAngle, 0.0, 0.0, 1); glColor3f (0.0, 1.0, 0.0); glBegin (GL_LINES); glVertex2f (-100, -100); glVertex2f (100, 100); glEnd (); glPopMatrix(); glPushMatrix(); glRotatef(-rotAngle, 0.0, 0.0, 1); glColor3f (0.0, 0.0, 1.0); glBegin (GL_LINES); glVertex2f (-100,100); glVertex2f (100, -100); glEnd (); glPopMatrix(); glPopMatrix(); glDisable(GL_LINE_SMOOTH); glDisable (GL_BLEND); glPushMatrix(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-450,150,-450,150,-10,10); glPushMatrix(); glRotatef(rotAngle, 0.0, 0.0, 1); glColor3f (0.0, 1.0, 0.0); glBegin (GL_LINES); glVertex2f (-100, -100); glVertex2f (100, 100); glEnd (); glPopMatrix(); glPushMatrix(); glRotatef(-rotAngle, 0.0, 0.0, 1); glColor3f (0.0, 0.0, 1.0); glBegin (GL_LINES); glVertex2f (-100,100); glVertex2f (100, -100); glEnd (); glPopMatrix(); glPopMatrix(); glEnable (GL_POINT_SMOOTH); glPushMatrix(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-450,150,-150,450,-10,10); glColor3f (0.0,0.0, 1.0); glBegin (GL_POINTS); glVertex2f(0,0); glEnd (); glPopMatrix(); glDisable (GL_POINT_SMOOTH); glPushMatrix(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-150,450,-150,450,-10,10); glColor3f (0.0, 1.0, 0.0); glBegin (GL_POINTS); glVertex2f(0,0); glEnd (); glPopMatrix(); glFlush(); } void reshape(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0,600,0,600,-10,10); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void keyboard(unsigned char key, int x, int y) { switch (key) { case 'r': case 'R': rotAngle += 20.; if (rotAngle >= 360.) rotAngle = 0.; glutPostRedisplay(); break; case 27: exit(0); break; default: break; } } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); glutInitWindowSize (600, 600); glutCreateWindow (argv[0]); init(); glutReshapeFunc (reshape); glutKeyboardFunc (keyboard); glutDisplayFunc (display); glutMainLoop(); return 0; }