Hello Nicolas,
From what I see, you are simply using two different depth- and stencil
buffers.
Try to share the depth buffer between the cameras by explicitly ataching
a depth texture. This should also share the stencil.
Is the depth buffer working as expected? Could you try if writing to the
depth buffer in the "stencil" pass actually is visible in the second pass.
cheers
Sebastian
Hello everyone.
I'm having trouble using the stencil buffer while doing a render to texture. My
purpose is to apply a black mask in front of my scene, as if I was looking at
the world through a crack in a wall. I managed to achieve this effect using the
stencil before. But back then I was doing direct rendering on the screen. Now
I'm trying to render to a texture and it doesn't work any more.
Here is what I do:
First I create the mask I want to draw into the stencil buffer. Here it's a
simple quad. I set a stencil function on it so it writes 1 into the stencil
buffer for each pixel.
Code:
osg::Vec3Array *vertices = new osg::Vec3Array();
vertices->push_back(osg::Vec3(0.25, 0.25, 0.0));
vertices->push_back(osg::Vec3(0.75, 0.25, 0.0));
vertices->push_back(osg::Vec3(0.75, 0.75, 0.0));
vertices->push_back(osg::Vec3(0.25, 0.75, 0.0));
_stencil_geometry = new osg::Geometry();
_stencil_geometry->setVertexArray(vertices);
_stencil_geometry->addPrimitiveSet(new osg::DrawArrays(GL_QUADS, 0, 4));
_stencil_node = new osg::Geode();
_stencil_node->addDrawable(_stencil_geometry);
_stencil_node->getOrCreateStateSet()->setMode(GL_LIGHTING,
osg::StateAttribute::OFF);
_stencil_node->getOrCreateStateSet()->setMode(GL_DEPTH_TEST,
osg::StateAttribute::OFF);
osg::Stencil* stencilSet = new osg::Stencil();
stencilSet->setFunction(osg::Stencil::ALWAYS, 1, ~0u);
stencilSet->setOperation(osg::Stencil::REPLACE, osg::Stencil::REPLACE,
osg::Stencil::REPLACE);
_stencil_node->getOrCreateStateSet()->setAttributeAndModes(stencilSet,
osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
Then I create a camera to render my mask into the stencil buffer. I make it so
that this camera clears the whole stencil to 0 before rendering.
Code:
_stencil_camera = new osg::Camera();
_stencil_camera->setViewport(0, 0, _w, _h);
_stencil_camera->setRenderOrder(osg::Camera::PRE_RENDER, 1);
_stencil_camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT |
GL_STENCIL_BUFFER_BIT);
_stencil_camera->setClearColor(Color(0., 0., 0., 1.));
_stencil_camera->setClearStencil(0);
_stencil_camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
_stencil_camera->setProjectionMatrixAsOrtho2D(0., 1., 0., 1.);
_stencil_camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
_stencil_camera->attach(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER,
GL_DEPTH_STENCIL_EXT);
_stencil_camera->addChild(_stencil_node);
Finally I create the camera that will render my scene and I attach the stencil
camera to it as a child. I set the render order so that this camera is rendered
after the stencil camera. I configure this camera to render into a texture and
I add it to the view.
Code:
_display_buffer = new osg::Texture2D();
_display_buffer->setTextureSize(_w, _h);
_display_buffer->setInternalFormat(GL_RGB);
_display_buffer->setFilter(osg::Texture2D::MIN_FILTER, _min_filter_mode);
_display_buffer->setFilter(osg::Texture2D::MAG_FILTER, _mag_filter_mode);
_display_camera = new osg::Camera();
_display_camera->setGraphicsContext(context);
_display_camera->setViewport(0, 0, _w, _h);
_display_camera->setRenderOrder(osg::Camera::PRE_RENDER, 2);
_display_camera->setClearColor(Color(0., 0., 0., 1.));
_display_camera->setClearMask(0);
_display_camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
_display_camera->addChild(_stencil_camera);
_display_camera->addChild(_my_scene_root_node);
_display_camera->setProjectionMatrixAsOrtho2D(0., 1., 0., 1.);
_display_camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
_display_camera->attach(osg::Camera::COLOR_BUFFER, _display_buffer);
_display_camera->attach(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER,
GL_DEPTH_STENCIL_EXT);
_view->addSlave(_display_camera, false);
Finally I set a stencil test on the whole scene. The scene shall only be drawn
on pixels where the stencil is not 0 (so whereever my mask was drawn).
Code:
osg::Stencil* stencilTest = new osg::Stencil();
stencilTest->setFunction(osg::Stencil::NOTEQUAL, 0, ~0u);
stencilTest->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP,
osg::Stencil::KEEP);
_my_scene_root_node->getOrCreateStateSet()->setAttributeAndModes(stencilTest,
osg::StateAttribute::ON);
Well, this doesn't work. All I get is a black texture (or whatever clear color
I set on my display camera). When I do the very same thing without the render
to texture part it works. But with the render to texture, it's as if my mask
was never drawn into the stencil buffer. What's weird is that if I configure my
stencil camera to clear the stencil buffer to a value different that 0 then my
scene is rendered to the texture. So it proves that the stencil works. But for
some reasons I don't understand my mask seems to never be drawn into it.
Could someone please tell me what I did wrong ?
Regards,
Nicolas
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=65335#65335
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
