首先，我想提一下，我发现了我认为完全相同的问题，遗憾的是没有答案，这里： Java Using OpenGL Stencil to create Outline
我将在下面发布我的代码，但首先是问题：从这个捕获**，你可以看到整个帧结构显示，而不是围绕球体的单行。我想摆脱所有这些内线！
**显然我无法添加图片：请参阅此链接 - 想象一个球体，四边形的所有边缘都可以看到大的3像素大线。
http://srbwks36224-03.engin.umich.edu/kdi/images/gs_sphere_with_frame.jpg
以下是给出结果的代码：
// First render the sphere:
// inside "show" is all the code to display a textured sphere
// looking like earth
sphe->show();
// Now get ready for stencil buffer drawing pass:
// 1. Clear and initialize it
// 2. Activate stencil buffer
// 3. On the first rendering pass, we want to "SUCCEED ALWAYS"
// and write a "1" into the stencil buffer accordingly
// 4. We don't need to actually render the object, hence disabling RGB mask
glClearStencil(0); //Edit: swapped this line and below
glClear(GL_STENCIL_BUFFER_BIT);
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_NEVER, 0x1, 0x1); //Edit: GL_ALWAYS
glStencilOp(GL_REPLACE, GL_KEEP, GL_KEEP); //Edit: GL_KEEP, GL_KEEP, GL_REPLACE
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glDepthMask(GL_FALSE); // As per Andon's comment
sphe->show();
// At this point, I expect to have "1" on the entire
// area covered by the sphere, so...
// 1. Stencil test should fail for anything, but 0 value
// RM: commented is another option that should work too I believe
// 2. The stencil op instruction at the point is somewhat irrelevant
// (if my understanding is correct), because we won't do anything
// else with the stencil buffer after that.
// 3. Re-enable RGB mask, because we want to draw this time
// 4. Switch to LINE drawing instead of FILL and
// 5. set a bigger line width, so it will exceed the model boundaries.
// We do want this, otherwise the line would not show
// 6. Don't mind the "uniform" setting instruction, this is so
// that my shader knows it should draw in plain color
// 7. Draw the sphere's frame
// 8. The principle, as I understand it is that all the lines should
// find themselves matched to a "1" in the stencil buffer and therefore
// be ignored for rendering. Only lines on the edges of the model should
// have half their width not failing the stencil test.
glStencilFunc(GL_EQUAL, 0x0, 0x1);
//glStencilFunc(GL_NOTEQUAL, 0x1, 0x1);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDepthMask(GL_TRUE);
glLineWidth(3);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
psa::shader::setUniform("outlining", 1);
sphe->show();
psa::shader::setUniform("outlining", 0);
现在只是为了证明一点，我厌倦了使用模板缓冲区做一些不同的事情 - 我只是想确保我的代码中的所有内容都已到位，以便它可以工作。
**遗憾的是，我很遗憾不会显示我得到的结果的屏幕截图：场景就像这样
http://mathworld.wolfram.com/images/eps-gif/SphereSphereInterGraphic_700.gif
但是较小的球体是不可见的（RGB掩模停用），并且可以通过孔看到世界背景（而不是更大球体的内部 - 面部剔除被停用）。
这就是代码......有趣的是，我可以更改许多内容，例如激活/停用STENCIL_TEST，将操作更改为GL_KEEP，或者甚至将第二个stencilFunc更改为＆＃34; NOT EQUAL 0＆＃34; ...结果总是一样的！我想我在这里缺少一些基本的东西。
void testStencil()
{
// 1. Write a 1 in the Stencil buffer for
// every pixels of the first sphere:
// All colors disabled, we don't need to see that sphere
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_ALWAYS, 0x1, 0x1);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glDepthMask(GL_FALSE); // Edit: added this
{
sphe->W = mat4::trans(psa::vec4(1.0, 1.0, 1.0)) * mat4::scale(0.9);
sphe->show();
}
// 2. Draw the second sphere with the following rule:
// fail the stencil test for every pixels with a 1.
// This means that any pixel from first sphere will
// not be draw as part of the second sphere.
glStencilFunc(GL_EQUAL, 0x0, 0x1);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDepthMask(GL_TRUE); // Edit: added this
{
sphe->W = mat4::trans(psa::vec4(1.2, 1.2, 1.2)) * mat4::scale(1.1);
sphe->show();
}
}
瞧瞧！如果有人能指出我正确的方向，我会非常感激。我还要确保将你的答案提到我找到的另一篇文章中。
答案 0 :(得分：0)
此问题中发布的OpenGL代码有效。问题的原因在窗口初始化/创建中出现：
以下分别是可用的代码的SDL1.2和SDL2版本。请注意，在两种情况下，SetAttribute语句都放在窗口创建之前。主要问题是错失位置的语句不一定会在运行时失败，但也不会起作用。
SDL1.2：
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
throw "Video initialization failed";
}
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES,16);
SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
const SDL_VideoInfo * i;
if((i = SDL_GetVideoInfo()) == NULL)
{
throw "Video query failed";
}
int flag = (fs ? SDL_OPENGL | SDL_FULLSCREEN : SDL_OPENGL);
if(SDL_SetVideoMode(w, h, i->vfmt->BitsPerPixel, flag) == 0)
{
throw "Video mode set failed";
}
glewExperimental = GL_TRUE;
if(glewInit() != GLEW_OK)
{
throw "Could not initialize GLEW";
}
if(!glewIsSupported("GL_VERSION_3_3"))
{
throw "OpenGL 3.3 not supported";
}
SDL2（基本上相同的代码，只是窗口创建功能改变）：
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
throw "Video initialization failed";
}
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES,16);
SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
int flag = SDL_WINDOW_OPENGL;
if((win = SDL_CreateWindow("engine", 100, 100, w, h, flag)) == NULL)
{
throw "Create SDL Window failed";
}
context = SDL_GL_CreateContext(win);
glewExperimental = GL_TRUE;
if(glewInit() != GLEW_OK)
{
throw "Could not initialize GLEW";
}
if(!glewIsSupported("GL_VERSION_3_3"))
{
throw "OpenGL 3.3 not supported";
}
值得一提的几点：
1。即使我明白不建议，SDL_GL_SetAttribute（SDL_GL_STENCIL_SIZE，1）也可以工作
2。在SDL2中，SDL_GL_SetAttribute SDL_GL_MULTISAMPLESAMPLES对我来说最多16，之后glewInit（）失败，但是，在窗口创建后移动多重采样设置并突然glewInit停止抱怨：我的猜测是它被忽略了。
3。在SDL1.2中，任何多重采样值似乎都可以工作
4。考虑到模板缓冲区功能，下面的代码也可以工作，但我发布它主要是为了提出一个问题：有多少属性设置实际工作？如何知道，因为代码编译并运行没有明显的问题？
// PROBABLY WRONG:
// ----
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
const SDL_VideoInfo * i;
if((i = SDL_GetVideoInfo()) == NULL)
{
throw "Video query failed";
}
int flag = (fs ? SDL_OPENGL | SDL_FULLSCREEN : SDL_OPENGL);
if(SDL_SetVideoMode(w, h, i->vfmt->BitsPerPixel, flag) == 0)
{
throw "Video mode set failed";
}
// No idea if the below is actually applied!
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 16);
SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);