Projection/View matrix 'flipping' help!

[al2950]

Hi all

I am currently trying to sort an issue with ogre not rendering cubemaps correctly. Basically when rendering to the cubemap I need to flip the render horizontally. As an example here is the a dynamic cubemapping demo I have done;

When rendering to the cubemap I want it to look like this;

Currently I have done this with the following code

Code: Select all

projectionMatrix[0][0] = -projectionMatrix[0][0]

However it ends up messing up the vertex winding so it only renders the backfaces of the models. Can anyone give me a helping hand here as the maths involved in projection matrices is not my forte!?

[xrgo]

Ogre 2.1? this?:
http://www.ogre3d.org/forums/viewtopic. ... 93#p522626

[al2950]

Unfortunately not . That changes it during sampling so although it fixes a dynamic cube map it breaks a normal 'static' cube map texture. This becomes very obvious/annoying when you use a static cube map texture as part of you skybox.

[xrgo]

That's strange, for me it solved it for dynamic AND static/texturefile cubemaps

[al2950]

That's strange, for me it solved it for dynamic AND static/texturefile cubemaps

Well it depends on how you think a cubemap should be sampled! But if you created a skybox using a static cubemap texture then used it in a dynamic cube map, then it would not work, unless you fudged all the areas in which you sampled the different cubemaps.

cubemaps are sample as if the texture is wrapped around the outside of the box and you sample it from the inside, hence normal sampling will always 'flip' the texture, and so why when writing to a cubemaps (from affectively inside the cube) you need to flip it again.

[xrgo]

=O that makes sense, thanks... and sorry I couldn't help

[scrawl]

Can you flip the sampling from the cubemap instead of flipping the rendering itself?

Or, you could apply the flip to the camera's view matrix (enableReflection), this way the scene manager should automatically invert the vertex winding for you. https://bitbucket.org/sinbad/ogre/src/9 ... r.cpp-1207