[druitres]

Hello,

after testing I encounter this bug:

when setting the scene scale to anything other than 1, the OGL preview for grass is off (for instance, setting scene scale to 0,1 results in a grass preview that is 10 times smaller than the geometry it's on)

- Jasper

[Mihai]

You mean comparing this to FIRE or main render? The grass params are in absolute values (cm or mm), so if you set the grass length to 50cm for example, leave the global scale at 1, you will get grass that's 50cm long in the render. If you now change the global scale to 0.1 your underlying geometry will be 10x smaller, but the grass blades will still be 50cm tall.

I guess the grass preview should keep track of the global scale setting to give you a better impression how big it is compared to the generating geometry...

[Mihnea Balta]

This is a bug indeed, it will be fixed in the next build. The viewport representation is scaled incorrectly so it doesn't follow the surface of the generator mesh if the scale is different than 1.0.

[druitres]

Thanks! Mihai: the OGL grass on a 10x10 plane when scene scale is set to 0,1 shows up as a patch of 1x1 - so it's scaled incorrectly compared to the generator mesh.

[Mihai]

Ah ok, I think though also it would be nice if the length parameter kept track of the scene scale setting to give you a correct view of how it will render.

[Mihnea Balta]

With the bug fix, the viewport preview will be accurate, but since the length is specified in fixed units (centimeters), changing the scene scale will change the size of the blades relative to the generator mesh. We can take into account the scale factor for the length too (so that it's actually specified in "SI units"), but then we should also take it into account for density, root width and tip width. Which option do you think is best?

[druitres]

Do you mean that entering a grass blade length of 10 cm will give blades of 10 cm only when scene scale is set to 1? In SI (much to my complete and continual bafflement) there is no absolute scale, although the manual suggests that 1 unit = 10 cm for correct dynamics. Hence my scene scale of 0,1; I always set up my scenes with 1 SI unit as 10 cm.

I would prefer 10 cm long grass to be 10 cm long relative to what I assume to be the size of my geometry.

So, entering metrics should take into account scene scale. Entering SI units should not. If you can provide both options that would be fine, but for me metrics always work best.