Hi Joel,
> layout (traingle_strip, max_vertices = 3) out;
I doubt this valid GLSL. Try
layout (triangle_strip, max_vertices = 3) out;
instead ;-)
Regards,
-Fred
----- "Joel Graff" <pair_o_gra...@comcast.net> a écrit :
> Hi,
>
> I've been developing an app in OpenSceneGraph to help me learn
> shaders. One component of that is to be able to visualize normals
> (surface, lighting, camera, etc.). I am attempting to implement
> geometry shaders to do this in GLSL 1.5 and OSG 2.9.9. At present,
> I've had success loading vertex and fragment shaders, but the geometry
> shader implementation eludes me.
>
> From what little I understand of geometry shaders and GLSL, I don't
> see anything wrong with my shader, but since I can't use RenderMonkey
> to test for compile errors, I could be wrong.
>
> That said, I've attempted to implement the shader (vertex, geometry
> and fragment), and I don't see any compile errors on the console when
> I run the program in debug mode (using VS2010) and break execution
> just before I run the viewer. I have set OSG_NOTIFY_LEVEL to DEBUG,
> so I expect that any compile problems with the shaders would be output
> to the console window. If not, and I have to retrieve the info log
> myself, I'd appreciate some info on how to do that, as attempting to
> do so generates an unhandled exception for me.
>
> Relevant code:
>
> Vertex Shader
>
>
> Code:
> #version 150
> uniform mat4 osg_ModelViewMatrix; //from application program.
> uniform mat4 osg_ModelViewProjectionMatrix;
> in vec4 osg_Vertex; //from vertex buffer from app pgm.
>
> void main (void) {
> gl_Position = osg_ModelViewMatrix * osg_Vertex;
> }
>
>
>
> Geometry Shader
>
>
> Code:
> #version 150
> layout (triangles) in;
> layout (traingle_strip, max_vertices = 3) out;
> uniform mat4 osg_ProjectionMatrix; //from application program.
> out vec3 normal; //to fragment shader.
>
> void main (void) {
> vec3 vector1;
> vec3 vector2;
>
> vector1 = gl_in[1].gl_Position.xyz - gl_in[0].gl_Position.xyz;
> vector2 = gl_in[2].gl_Position.xyz - gl_in[0].gl_Position.xyz;
>
> normal = normalize (cross (vector1, vector2));
> gl_Position = osg_ProjectionMatrix * gl_in[0].gl_Position;
> EmitVertex ();
>
> gl_Position = osg_ProjectionMatrix * gl_in[1].gl_Position;
> EmitVertex ();
>
> gl_Position = osg_ProjectionMatrix * gl_in[2].gl_Position;
> EmitVertex ();
>
> EndPrimitve ();
> }
>
>
>
> Fragment Shader
>
>
> Code:
> #version 150
> in vec3 normal; //from geometry shader.
> out vec4 color; //to framebuffer.
>
> void main (void) {
> gl_FragColor = vec4 (normal, 1.0);
> }
>
>
>
> OSG Code
>
>
> Code:
> void loadShaders (osg::ref_ptr<osg::Group> rootGroup)
> {
> osg::ref_ptr<osg::Geode> rootGeode (dynamic_cast<osg::Geode *>
> (FindNode(rootGroup, "geode_root")->getFirst()));
> osg::ref_ptr<osg::Geometry> SAQgeometry (FindGeometry(rootGeode,
> "geometry_ScreenAlignedQuad"));
>
> osg::ref_ptr<osg::Shader> vertexShader(
> osg::Shader::readShaderFile (osg::Shader::VERTEX,
> "C:/OpenSceneGraph/OpenSceneGraph-Data-2.8.0/myShaders/test.vert"));
>
> osg::ref_ptr<osg::Shader> geometryShader(
> osg::Shader::readShaderFile (osg::Shader::GEOMETRY,
> "C:/OpenSceneGraph/OpenSceneGraph-Data-2.8.0/myShaders/test.geom"));
>
> osg::ref_ptr<osg::Shader> fragShader(
> osg::Shader::readShaderFile (osg::Shader::FRAGMENT,
> "C:/OpenSceneGraph/OpenSceneGraph-Data-2.8.0/myShaders/test.frag"));
>
> osg::ref_ptr<osg::Program> program (new osg::Program());
>
> program->addShader(vertexShader); //new
> osg::Shader(osg::Shader::VERTEX, vertexShaderSource));
> program->addShader(geometryShader);
> program->addShader(fragShader); //new
> osg::Shader(osg::Shader::FRAGMENT, fragmentShaderSource));
>
> program->setParameter( GL_GEOMETRY_VERTICES_OUT_EXT, 3 );
> program->setParameter( GL_GEOMETRY_INPUT_TYPE_EXT,
> GL_TRIANGLE_STRIP );
> program->setParameter( GL_GEOMETRY_OUTPUT_TYPE_EXT,
> GL_TRIANGLE_STRIP );
>
> program->addBindAttribLocation("osg_Vertex", 0);
> program->addBindAttribLocation("osg_Normal", 2);
>
> SAQgeometry->getOrCreateStateSet()->setAttribute(program);
> ////////////////////////////////////////
>
> osg::ref_ptr<osg::StateSet> ss = SAQgeometry->getStateSet();
> ...
> }
>
>
>
> Just to ensure there's nothing wrong with my OSG code, I commented out
> the geometry shader-related code and had the frag shader color the
> primitive yellow and it worked perfectly.
>
> Anyway, I've looked for answers and I'm finding geometry shader
> information, esp. as it relates to OSG is (not surprisingly) somewhat
> sparse.
>
> I appreciate any thoughts / comments / tips that anyone may have.
>
> Thanks.
>
> Joel
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=34101#34101
>
>
>
>
>
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> osg-users mailing list
> osg-users@lists.openscenegraph.org
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