Hello, Preface: I realize this question comes about because I've never really learned OpenGL/GLSL from the ground up and am likely missing some simple concepts, but I mostly have been coasting by at the osg middleware level and have been doing OK so far.
If I want to do some simple post-processing I can create a render-to-texture camera and render to the framebuffer. I can attach a texture to the framebuffer and then create another "screen" camera to render that texture to the screen. I can add a GLSL shader program to this texture so that before the texture gets rendered to the screen it gets an effect added to it using the shaders. When I use shaders attached to 3-D model nodes in the scene itself, the meaning of the vertex and frag shaders is easy to understand->the vertices of the 3-D model are the vertices referenced in the vertex shader. However, When I render my scene to a texture and then do a simple pass-through vertex and frag shader combo, what is the meaning of the vertices in this scenario? I had assumed that once you render your scene to a texture, all knowledge of the original scene's geometry and vertex locations has been lost, is this true? If so, then what vertices am I dealing with? It's easy enough to follow along with examples and to use a simple pass-through vertex shader, but I'd like to understand this better because I now want to insert a geometry shader in between the vertex and frag shaders and again I'm not sure whether to use point, line, or triangle in my geometry shader as the primitive type because I thought that the geometry and primitives of the original scene would b e lost after rendering to texture. What am I missing here? Any clarification is most welcome. -Ethan ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=57281#57281 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
