I don"t know where to submit this post. As it is related to a problem using animated texture, I hope that it is the good place…
Here is the problem :
I’m still working on my Tracks Creator,and including it in my 4x4 Autodrive system.
I have encountered a very annoying trouble while using an animated texture (sequence of images) to animate wheels tracks in grass.
For Blender users who have read my tutorial about the Tracks Creator, I said that I used fields instead of Texture settings in the Map To panel, because I had difficulties with it. This time, I decided to dig more in depth with this panel, and what I have found seems to be a bug.
Here is the panel I used :
It works fine on a still picture, and I have got the expected result :
It is what I wanted : The grass is like crushed in the sand and not visible in the tracks.
The tracks in the sand are made thanks to a displace modifier (the ground is subdivided enough) and also have the details enhanced by both a Color and a Nor parameter. The tracks in grass are done with the Particles settings of the Map To panel applied on the grass material. The area where there is grass is defined by a vertex group declared in the particle system.
Everything is fine on a still picture, but the problem is that it doesn’t work in an animation !
It appears that the new frame of the animated texture is loaded only each time you enter and exit of the Edit mode ! In the ordinary process of the animation or the rendering, the texture sequence frames are refreshed for the displacement modifier, but are not for the Map To parameters of the texture.
Here is what I get in an animation :
The grass is moved, because it grows onto a ground mesh which is deformed by the Displacement Modifier, but the grass particles (velocity and density) are not affected by the material Map To texture settings… until I select the ground mesh and Enter/Exit Edit mode.
As I started the project on Blender v2.48a, I have done a trial with v2.49a to see if there was a difference. There is one difference, but not the expected one. The trouble in animation is the same, but the image when rendering a still picture looks different, with exactly the same settings that I used for the first image :bit
After making a simplified scene with similar settings, I have discovered that in Blender v2.49a, the button Dens (for Density) of the Particles settings in the Map To Panel has no effect ! So, in this third image only the IVel (Initial Velocity) Button has an effect on the particles. In the first image, instead, both Dens and IVel buttons are active, and there is no grass at all in the tracks. Even if the third image is more realistic, the behaviour of the Dens button is not the expected one !
What is your opinion about that ?
Currently, this trouble ruins a part of my efforts on the Tracks Creator, because I have to switch back to the field method which is less accurate and harder to setup.
My most recent test with the Tracks Creator and my 4x4 Autodrive system (still no good sequence with grass, due to the explained trouble :
The same on vimeo :
Below, I put two links : The simplified Blend file and a Zip file containing a sequence of 100 jpg images (Animated tracks) to be used with the blend file, for the Ground Displacement texture and the Grass particles Density.
Thanks in advance for any idea.
Edit : Well, as I got no response, I have submitted a report to the Bugtracker.