I tried to scale the top two vertices of a plane in the uv editor and got this weird triangular distortion. Anyone know why this is?
Thanks
it’s quite normal… the problem is because the triangulation makes the area of one triangle bigger than the other. (just imagine a line between the top-left vertex and the botton-right, and if you count the darkgrey squares in each new area, you’ll find they are thee same in your render)
This is a rather known limitation of 3d graphics!
Subdividing the mesh is not perfect, but having texture created for the UV/mesh is the best way to overcome the distortion.
Do you realy need the UV to look like that?
Subdividing the mesh is not perfect, but having texture created for the UV/mesh is the best way to overcome the distortion.
Right! I agree.
Subdivide at a resolution as close to pixel as possible. In the example above, maybe as these b and w squares are. It should be efficient.
The well known limitation of 3d graphics. There isn’t any quad in the 3d graphics reality. Only tris.
Not a blender issue.
you could modify the checkerboard texture in Gimp to fit your face!
happy bl
Ah yes, I see. If you triangulate the quad and view stretching in the uv editor, one of the triangles becomes very stretched. Subdividing the mesh and using linear proportional editing in the uv editor could approximate the effect I was going for but I had trouble getting large differences in scale between the two sides of the plane. Gimp could also work. However, ideally if it can be done in blender that is best. Here is what I came up with:
I ended up using nodes from blender cookie’s “Custom UV Transformation Nodes for Cycles” (http://cgcookie.com/blender/cgc-courses/custom-uv-transformation-nodes-cycles/) so I cannot show what is in the translate and scale nodes but their names describe exactly what they do. Essentially what these nodes do is change the X scale of the texture coordinates based on the Y position. So with increasing Y position in the texture grid, the X scale is decreased. This creates the effect of converging lines. In order to achieve this effect, the center of uv vertices must be placed at (0,0) of the texture coordinates (see uv editor in image). I believe the uv vertices are scaled in relation to this point. My intent was to use this to fake perspective with lawn lines in my grass scene so I didn’t have to increase the plane size and render out much more grass particles. I don’t know if this ended up saving any render time (I have not compared) haha but it was a fun exercise with uvs and nodes. Regardless of time saved rending, though, adjusting nodes is much faster than extending a plane and adding more particles every time I want to make an adjustment.
Thanks to everyone who viewed and commented!