为什么 OpenGL 的抗锯齿功能不起作用？

Question

我一直在研究如何在OpenGL中使用抗锯齿。 这里是我找到的教程。

示例 6-5 是一个小程序，旨在演示多边形的抗锯齿功能。

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

GLboolean polySmooth = GL_TRUE;
static void init(void)
{
    glCullFace(GL_BACK);
    glEnable(GL_CULL_FACE);
    glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
    glClearColor(0.0, 0.0, 0.0, 0.0);
}

#define NFACE 6
#define NVERT 8
void drawCube(GLdouble x0, GLdouble x1, GLdouble y0,
              GLdouble y1, GLdouble z0, GLdouble z1)
{
    static GLfloat v[8][3];
    static GLfloat c[8][4] = {
        {0.0, 0.0, 0.0, 1.0}, {1.0, 0.0, 0.0, 1.0},
        {0.0, 1.0, 0.0, 1.0}, {1.0, 1.0, 0.0, 1.0},
        {0.0, 0.0, 1.0, 1.0}, {1.0, 0.0, 1.0, 1.0},
        {0.0, 1.0, 1.0, 1.0}, {1.0, 1.0, 1.0, 1.0}
    };

/*  indices of front, top, left, bottom, right, back faces  */
    static GLubyte indices[NFACE][4] = {
        {4, 5, 6, 7}, {2, 3, 7, 6}, {0, 4, 7, 3},
        {0, 1, 5, 4}, {1, 5, 6, 2}, {0, 3, 2, 1}
    };

    v[0][0] = v[3][0] = v[4][0] = v[7][0] = x0;
    v[1][0] = v[2][0] = v[5][0] = v[6][0] = x1;
    v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
    v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
    v[0][2] = v[1][2] = v[2][2] = v[3][2] = z0;
    v[4][2] = v[5][2] = v[6][2] = v[7][2] = z1;

#ifdef GL_VERSION_1_1
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glVertexPointer(3, GL_FLOAT, 0, v);
    glColorPointer(4, GL_FLOAT, 0, c);
    glDrawElements(GL_QUADS, NFACE * 4, GL_UNSIGNED_BYTE, indices);
    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);
#else
    printf("If this is GL Version 1.0, ");
    printf("vertex arrays are not supported.\n");
    exit(1);
#endif
}

/*  Note:  polygons must be drawn from front to back
 *  for proper blending.
 */
void display(void)
{
    if (polySmooth)
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glEnable(GL_BLEND);
        glEnable(GL_POLYGON_SMOOTH);
        glDisable(GL_DEPTH_TEST);
    }
    else
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDisable(GL_BLEND);
        glDisable(GL_POLYGON_SMOOTH);
        glEnable(GL_DEPTH_TEST);
    }

    glPushMatrix();
    glTranslatef(0.0, 0.0, -8.0);
    glRotatef(30.0, 1.0, 0.0, 0.0);
    glRotatef(60.0, 0.0, 1.0, 0.0);
    drawCube(-0.5, 0.5, -0.5, 0.5, -0.5, 0.5);
    glPopMatrix();

    glFlush();
}

void reshape(int w, int h)
{
    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(30.0, (GLfloat) w / (GLfloat) h, 1.0, 20.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
    switch (key)
    {
    case 't':
    case 'T':
        polySmooth = !polySmooth;
        glutPostRedisplay();
        break;
    case 27:
        exit(0);        /*  Escape key  */
        break;
    default:
        break;
    }
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_ALPHA | GLUT_DEPTH);
    glutInitWindowSize(200, 200);
    glutCreateWindow(argv[0]);
    init();
    glutReshapeFunc(reshape);
    glutKeyboardFunc(keyboard);
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}

我将代码复制到我的计算机（Ubuntu 11）上，编译它并得到：

阅读代码，我认为当按下 t 按钮时，多边形应该是抗锯齿的。这张照片是我按下t按钮后拍摄的。据我所知，我不认为这些是抗锯齿多边形，我的做法有问题吗？

Answer 1

POLYGON_SMOOTH 没用（不要相信红皮书^^）。大多数显卡都没有实现这一点。

只需在 glutInitDisplayMode() 中添加“| GLUT_MULTISAMPLE”即可。这将使用 MSAA 技术（多重采样 AA）添加全屏（好吧，全窗口）抗锯齿。如果不起作用，请尝试使用 freeglut。您可以在这里找到 opengl 示例：OpenGL 示例包，他们使用 freeglut。