OpenGL学习十三：多边形偏移
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做法：
1.启用偏移模式
??? glEnable(GL_POLYGON_OFFSET_LINE|GL_POLYGON_OFFSET_POINT|GL_POLYGON_OFFSET_FILL);
分别对应GL_FILL,GL_POINT,GL_LINE
2.设置偏移量
??? glPolygonOffset(polyfactor, polyunits);
偏移量算法很复杂建议都设置为1.0
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#include "header.h"GLuint list;GLint spinx = 0;GLint spiny = 0;GLfloat tdist = 0.0;GLfloat polyfactor = 1.0;GLfloat polyunits = 1.0;void display (void){ GLfloat gray[] = { 0.8, 0.8, 0.8, 1.0 }; GLfloat black[] = { 0.0, 0.0, 0.0, 1.0 }; glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushMatrix (); glTranslatef (0.0, 0.0, tdist); glRotatef ((GLfloat) spinx, 1.0, 0.0, 0.0); glRotatef ((GLfloat) spiny, 0.0, 1.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, gray); glMaterialfv(GL_FRONT, GL_SPECULAR, black); glMaterialf(GL_FRONT, GL_SHININESS, 0.0); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_POLYGON_OFFSET_FILL); glPolygonOffset(polyfactor, polyunits); glCallList (list); glDisable(GL_POLYGON_OFFSET_FILL); glDisable(GL_LIGHTING); glDisable(GL_LIGHT0); glColor3f (1.0, 1.0, 0.0); glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); glCallList (list); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glPopMatrix (); glFlush ();}void gfxinit (void){ GLfloat light_ambient[] = { 0.0, 0.0, 0.0, 1.0 }; GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat light_specular[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 }; GLfloat global_ambient[] = { 0.2, 0.2, 0.2, 1.0 }; glClearColor (0.0, 0.0, 0.0, 1.0); list = glGenLists(1); glNewList (list, GL_COMPILE); glutSolidSphere(1.0, 20, 12); glEndList (); glEnable(GL_DEPTH_TEST); glLightfv (GL_LIGHT0, GL_AMBIENT, light_ambient); glLightfv (GL_LIGHT0, GL_DIFFUSE, light_diffuse); glLightfv (GL_LIGHT0, GL_SPECULAR, light_specular); glLightfv (GL_LIGHT0, GL_POSITION, light_position); glLightModelfv (GL_LIGHT_MODEL_AMBIENT, global_ambient);}void reshape(int width, int height){ glViewport (0, 0, width, height); glMatrixMode (GL_PROJECTION); glLoadIdentity (); gluPerspective(45.0, (GLdouble)width/(GLdouble)height, 1.0, 10.0); glMatrixMode (GL_MODELVIEW); glLoadIdentity (); gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);}void mouse(int button, int state, int x, int y) { switch (button) {case GLUT_LEFT_BUTTON: switch (state) {case GLUT_DOWN: spinx = (spinx + 5) % 360; glutPostRedisplay(); break;default: break; } break;case GLUT_MIDDLE_BUTTON: switch (state) {case GLUT_DOWN: spiny = (spiny + 5) % 360; glutPostRedisplay(); break;default: break; } break;case GLUT_RIGHT_BUTTON: switch (state) {case GLUT_UP: exit(0); break;default: break; } break; default: break; }}void keyboard (unsigned char key, int x, int y){ switch (key) { case 't': if (tdist < 4.0) { tdist = (tdist + 0.5); glutPostRedisplay(); } break; case 'T': if (tdist > -5.0) { tdist = (tdist - 0.5); glutPostRedisplay(); } break; case 'F': polyfactor = polyfactor + 0.1; printf ("polyfactor is %f\n", polyfactor); glutPostRedisplay(); break; case 'f': polyfactor = polyfactor - 0.1; printf ("polyfactor is %f\n", polyfactor); glutPostRedisplay(); break; case 'U': polyunits = polyunits + 1.0; printf ("polyunits is %f\n", polyunits); glutPostRedisplay(); break; case 'u': polyunits = polyunits - 1.0; printf ("polyunits is %f\n", polyunits); glutPostRedisplay(); break; default: break; }}int main(int argc, char** argv){ glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutCreateWindow(argv[0]); glutReshapeFunc(reshape); glutDisplayFunc(display); glutMouseFunc(mouse); glutKeyboardFunc(keyboard); gfxinit(); glutMainLoop(); return 0;}?