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Picking out and modifying a texel on a texture on a rendered mesh

General and Gameplay Programming Programming

Started by KaiserJohan February 19, 2017 10:51 PM

0 comments, last by Hodgman 7 years, 2 months ago

KaiserJohan

2,320

Author

February 19, 2017 10:51 PM

As the title says :)

Using my mouse, I want to pick out a texel on a mesh I have rendered and modify that texel.

I start by picking a screen coordinate using my mouse. I then convert this screen coordinate to a world coordinate (using depth value at that pixel + inverse wvp matrix). This world coordinate is on the mesh at the pixel of the texture I want to modify. The question is how do I then go from world coordinate to texture coordinate on that specific texture?

Hodgman

52,717

February 19, 2017 11:03 PM

You've got to find which triangle is at that world coordinate (e.g. ray-trace along a ray from the eye to that world coordinate against all the triangles), and then convert from world coordinates to barycentric coordinates, and use those to interpolate the texture-coordinates from the three vertices, then convert the texel coordinates into a pixel address.

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