July 06, 2011, 02:56:19 pm

FINALLY found a solution.

It was an error in Speed tree wind algorithm. As it turns out the amount of wind depends on the height of a vertex.

So, for the trunk there are some vertices with y=0. In the shader there is a line which raises this value to a certain power. Normally raising 0 to the power of 2 should result in 0.

However, in HLSL the compiler implements the pow(0,2) function as: exp(log(0) * 2) which results in NaN causing the polygons with those vertices to disappear.

Will be fixed in next update!