i'm trying to generate a decal mesh kinda like this: http://blog.wolfire.com/2009/06/how-to-project-decals/

but instead of projecting the decal with a box, i need to project it with a sort of triangular space. the "decal space" will have a start triangle and an end triangle. the end triangle isn't necessarily the same size as the start triangle and it isn't necessarily parallel to it and it can be rotated.

i need to be able to transform coordinates into that space and back out. how can i do that? can you do that with a normal 4x4 matrix?

  • \$\begingroup\$ Can you clarify what this alternative projection space accomplishes? The more we can understand your application and why you want to do this, the better we can target answers to meet your needs. Mock-up images or diagrams can often help to clarify when asking graphical or spatial questions. \$\endgroup\$
    – DMGregory
    Apr 30 '20 at 22:59
  • \$\begingroup\$ i want to create a projected decal mesh, but instead of using a box for projection, i want to use another mesh. that mesh is a sort-of 2D mesh, basically a flat mesh generated from a spline. the reason i thought i needed a transformation like that is if i just project the trianges based on the whole triangle, that would create gaps between the projections of the triangles. so i figured i should project based on the normals of the vertices of the spline-mesh. but then i would need the kind of transform i asked about, i think. \$\endgroup\$
    – Matthias
    May 2 '20 at 7:18
  • \$\begingroup\$ Definitely take a step back then, and edit your question ti show us an example of this spline mesh, and how you want the projection to map relative to it. \$\endgroup\$
    – DMGregory
    May 2 '20 at 12:16

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