我继续在OpenGL中处理阴影卷,在finishing with volume itself之后,我需要使用模板缓冲区绘制阴影,那就是我被卡住了:)我渲染了这个场景:http://prntscr.com/17lyr 如你所见,球体代表光源,一个蘑菇的体积直接绘制到屏幕上,一个没有(我希望看到阴影)。它们完全相同,是将一个模型转换为X轴上的一些单位。以下是我正在使用的代码:
void Display(){
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glLoadIdentity();
glLightfv(GL_LIGHT1,GL_POSITION,light_position[0]);
cam.SetPrespective();
DrawDebugObject(true);
glTranslatef(15,0,0);
DrawDebugObject(false);
glFinish();
glutSwapBuffers();
}
void DrawDebugObject(bool draw_sil){
glPushMatrix();
glTranslatef(light_position[1][0],light_position[1][1],light_position[1][2]);
glColor3ub(255,255,0);
gluSphere(gluNewQuadric(),0.5,10,10);
glPopMatrix();
glDisable(GL_LIGHTING);
glBegin(GL_QUADS);
glColor3f(1,1,1);
glVertex3f(-100,0,-100);
glVertex3f(-100,0,100);
glVertex3f(100,0,100);
glVertex3f(100,0,-100);
glEnd();
glEnable(GL_LIGHTING);
pModel->draw();
if(draw_sil)
pModel->markSilouette(light_position[1]);
castShadow(pModel,light_position[1]);
}
void castShadow(Model* model,float* lp){
glDisable(GL_LIGHTING);
glDepthMask(GL_FALSE);
glDepthFunc(GL_LEQUAL);
pModel->markVisible(lp);
glEnable(GL_STENCIL_TEST);
glColorMask(0, 0, 0, 0);
glStencilFunc(GL_ALWAYS, 1, 0xffffffff);
// first pass, stencil operation decreases stencil value
glFrontFace(GL_CCW);
glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
pModel->markSilouette(lp);
// second pass, stencil operation increases stencil value
glFrontFace(GL_CW);
glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
pModel->markSilouette(lp);
glFrontFace(GL_CCW);
glColorMask(1, 1, 1, 1);
//draw a shadowing rectangle covering the entire screen
glColor4f(1.0f, 0.0f, 0.0f, 0.4f);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glStencilFunc(GL_NOTEQUAL, 0, 0xffffffff);
glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
glPushMatrix();
glLoadIdentity();
glBegin(GL_QUADS);
glVertex3f(-0.1f, 0.1f,-0.10f);
glVertex3f(-0.1f,-0.1f,-0.10f);
glVertex3f( 0.1f, 0.1f,-0.10f);
glVertex3f( 0.1f,-0.1f,-0.10f);
glEnd();
glPopMatrix();
glDisable(GL_BLEND);
glDepthFunc(GL_LEQUAL);
glDepthMask(GL_TRUE);
glEnable(GL_LIGHTING);
glDisable(GL_STENCIL_TEST);
}
这是我的GL初始化函数:
void InitGL(){
glEnable(GL_NORMALIZE);
glEnable(GL_LIGHTING);
glEnable(GL_TEXTURE_2D);
glShadeModel(GL_SMOOTH);
glClearDepth(1.0f); // Depth Buffer Setup
glClearStencil(0); // Stencil Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
glHint(GL_FOG_HINT, GL_NICEST);
...nothing important after that
在我的主要功能中:
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGB|GLUT_DEPTH|GLUT_DOUBLE|GLUT_STENCIL|GLUT_ACCUM);
glutInitWindowSize(Width,Height);
glutCreateWindow("Spheres");
glutDisplayFunc(Display);
glutReshapeFunc(Reshape);
glutKeyboardFunc(Keyboard);
glutKeyboardUpFunc(KeyboardUp);
glutTimerFunc(TIMEOUT,Timer,TIMEOUT);
glutPassiveMotionFunc(MouseMove);
我的代码一切正常吗?因为我看不到阴影,甚至不知道如何检查模板值是否设置正确。
答案 0 :(得分:0)
没有办法检查模板。我假设你正在使用深度失败。我建议像这样使用glStencilOpSeperate。
glClear(GL_STENCIL_BUFFER_BIT);
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glEnable(GL_STENCIL_TEST);
glEnable(GL_POLYGON_OFFSET_FILL);
glDisable(GL_CULL_FACE);
glStencilFunc(GL_ALWAYS, 0x00, 0xFF);
glStencilOpSeparate(GL_FRONT, GL_KEEP, GL_INCR_WRAP, GL_KEEP);
glStencilOpSeparate(GL_BACK, GL_KEEP, GL_DECR_WRAP, GL_KEEP);
glPolygonOffset(0.0f, 5.0f);
glDepthFunc(GL_LESS);
然后,当您绘制实际几何体时,请确保替换模板值,如下所示:
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glEnable(GL_CULL_FACE);
glDisable(GL_POLYGON_OFFSET_FILL);
glCullFace(GL_BACK);
glDepthFunc(GL_GEQUAL);
glStencilFunc(GL_EQUAL, 0x00, 0xFF);
glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE);