How to make a texture always face the camera?

Questions
21

For that example, you could just have added the plane as child to the camera, with the appropriate offset. If you need a moving plane, but still want the plane to face the camera, you can do like I did for each sphere in my spheres example. The principle is to add the vertex position in view space. For just a single object, you could just add in a uniform position that you apply the modelViewMatrix to, and then add the vertex position before applying the projectionMatrix. (Or even projecting first and adding in the projected space.)

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You are right. Making the plane a child to the camera would have been an improvement and saved some calculations. That particular project turned out to be a dead end because of performance issues. However, I was hoping that the equations would be useful for purposes of this thread.

But as I read the discussion of your project, I was reminded that what I designed is commonly called a “billboard” and there are probably a million examples of how to create those.

So, in this case, my reply - while well intended - probably contributes nothing useful to this thread and can be ignored.

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I think in general having multiple methods in the arsenal can be useful. :smiley:
(Edit: removed off-topic stuff)

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(Edit: removed off-topic reply)

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(Edit: removed off-topic stuff)

@ken.kin So, for a on-topic (but still blind) advice:

  • I suggest computing (as needed) a (not necessarily the smallest) bounding sphere for the geometry (geometry.computeBoundingSphere(), geometry.boundingSphere), and scaling it by the object scale (assumed uniform for now).
  • Pass the view-space center and radius of the sphere to the shaders. (E.g. using object.onBeforeRender.)
  • In the vertex shader, make sure to calculate view space position of the vertex and pass it in a varying. ( viewMatrix*vec4(position, 1.);)
  • In the fragment shader, transform view space xy position by subtracting the sphere center, dividing by two times the sphere radius and adding vec2(1.0). (vec2 uv = (viewPos.xy-sphereCenter.xy)/(2.*sphereRadius)+vec2(1.);)
  • The resulting vector is an uv for the texture lookup. (vec4 color = texture2D(map, uv);)
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(Edit: removed off-topic reply)