A couple of oddities

Started by Kevin F, November 02, 2010, 11:33:57 am

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Kevin F

A couple of things that have puzzled me for a while:
In the painted shader there are options to use either "absolute brush" or "view-relative brush" and to select a size within each. Now if you select absolute the brush size changes depending where in the scene it is, and increases or decreases as it moves to and from the camera i.e. view-relative. Whereas the view-relative option keeps the brush size constant no matter where it is! Is this not the wrong way round or is it just that I don't understand what it's doing?

Another similar apparent reversal is in the image map shader. If you select an image for projection and position it at "position centre" the preview window shows the map in the lower left side, but if you position it at "position lower left" the preview shows it centrally!

Again it could just be me, or it could be an error in the program?

Tangled-Universe

I understand your confusion about the painted shader.
For both ways I'd tend to say it's correct.
Absolute probably means that the size of the mask is of similar size everywhere you draw in the landscape whereas relative will change the size of the mask on the terrain as the brush size is fixed by the screen-resolution and not terrain.

The coordinates for the heightfield- and image-mapshader are sometimes a bit confusing too.
Generally centre means that the image will be centred at the coordinates.
So say you have a 2000x2000 sized image and set it to "centre" then the image will span coordinates: -1000,-1000 to 1000,1000.
If you'd put that on "lower left" it would be: 0,0 to 2000,2000.

Kevin F

Thanks T-U, I understand the image mapping issue now, but I'm still not convinced/sure about the painted shader.
Shouldn't the size of the "view-relative" brush be relative to the camera? i.e. nearer = bigger, distant = smaller,
and the absolute brush be a fixed size relative to the camera, no matter where in the scene it is?

dandelO

The painted shader 'absolute' setting means that the brush will react accordingly to the depth your brush reaches 'into' the preview in 3D space, i.e. if you paint close to the camera with a 10m brush and then extend the stroke further into the scene, the brush will appear to shrink because it's keeping the same 'absolute' 10m scale, in relation to the surface it is painting on.
'View relative' means preview window relative, meaning that the brush is the same size in your preview, regardless of what 'depth' into the 3D space you paint.
Another good point to note, using the 'absolute' brush can crash the program erratically when painting on the sky. If you use 'view relative', it doesn't crash.

Tangled-Universe

Quote from: Kevin F on November 02, 2010, 12:33:53 pm
Thanks T-U, I understand the image mapping issue now, but I'm still not convinced/sure about the painted shader.
Shouldn't the size of the "view-relative" brush be relative to the camera? i.e. nearer = bigger, distant = smaller,
and the absolute brush be a fixed size relative to the camera, no matter where in the scene it is?


It depends a bit on how you look at it, but as you can see the other Martin also responded to this and he explains the same thing as me only perhaps in better words than me :)