Hi Robin, I'm a bit perplexed by the issue, as the uniform should be tracking the modelview matrix directly as osg::State does a substitution.
Could you create a small code example that reproduces the problem? Robert. On 25 March 2015 at 01:28, Robin Wu <[email protected]> wrote: > Hi all, > > Recently, I discovered a weird issue that the view/Proj matrix in the main > camera updated by the default cameramanipulator of osgViewer does not sync > with the one I got in the shader, e.g gl_ModelViewMatrix, > gl_ProjectionMatrix. > > The following two code snippets produce different results. > The first one is using the built in gl_ModelViewProjectionMatrix uniform > passed in during renderingTraversals() > > The second one is using the properties from _viewer->getCamera() as > uniforms, e.g mainCamera->getViewMatrix(). > > > Code: > > void main() > { > gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; > } > > > > > > Code: > > uniform mat4 u_modelMatrix; > uniform mat4 u_viewMatrix; > uniform mat4 u_projMatrix; > > mat4 getModelToWorldMatrix() > { > return osg_ViewMatrixInverse * gl_ModelViewMatrix; > } > > void main() > { > gl_Position = u_projMatrix * u_viewMatrix * getModelToWorldMatrix() * > gl_Vertex; > } > > > > > When overlapping the rendering results of the two shaders into one buffer, > the second shader is approximately one frame slower than the first one, > making me doubt that the view/proj matrix managed by the main camera is not > synced with the one managed by the renderingTraversals(). > > This out of sync problem is also pronounced in Wang Rui's > effectcompositor. In the ssao.xml demo, if you turn on the analysis mode, > you'll see that in the linearDepth buffer view, the depth is unstable > (flickering) when you zoom in and out quickly. > > The following is the code snippet from Rui's ssao.xml > > Code: > > void main(void) > { > vec4 vecInEye = gl_ModelViewMatrix * gl_Vertex; > depthValue = (-vecInEye.z - nearPlaneValue) / (farPlaneValue - > nearPlaneValue); > gl_Position = ftransform(); > } > > > > > I suspect that the nearPlaneValue and farPlaneValue form the built-in > projection matrix's uniforms are somehow not synced with the corresponding > ones in gl_ProjectionMatrix ( from ftransfrom() ); > > This problem bugs me for a long time. My current workaround is just using > the manually supplied uniforms from the main camera. But the extra > computation of the modelviewprojecionmatrix is definitely a waste in the > vertex shader. > > Any ideas? > > Thank you. > > ... > > Robin[/code] > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=63199#63199 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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