I'm rendering a particle system of vertices, which are then tessellated into quads in a geom shader, and textured/rendered as point sprites. Then they are scaled in size depending on how far away they are from the camera. I'm trying to render out every frame of my scene into cube maps. So essentially I place six cameras into my scene and point them in each direction for the face of the cube and save an image.
My point sprites are of varying sizes. When they near the border of one camera, (if they are large enough) they appear in two cameras simultaneously. Since point sprites are always facing the camera, this means that they are not continuous along the seam when I wrap my cube map back into 3d space. This is especially noticeable when the points are quite close to the camera, as the points are larger, and stretch further across into both camera views. I'm also doing some alpha blending, so this may be contributing to the problem as well.
I don't think I can just cull points that near the edge of the camera, because when I put everything back into 3d I'd think there would be strange areas where the cloud is more sparsely populated. Another thought I had would be to blur the edges of each camera, but I think this too would give me a weird blurry zone when I go back to 3d space. I feel like I could manually edit the frames in photoshop so they look ok, but this would be kind of a pain since it's an animation at 30fps.
The image attached is a detail from the cube map. You can see the horizontal seam where the sprites are not lining up correctly, and a slightly less noticeable vertical one on the right side of the image. I'm sure that my camera settings are correct, because I've used this same camera setup in other scenes and my cubemaps look fine.
Anyone have ideas?
I'm doing this in openFrameworks / openGL fwiw.
Instead of facing the camera, make them face the origin of the cameras? Not sure if this fixes everything, but intuitively I'd say it should look close to OK. Maybe this is already what you do, I have no idea.
(I'd like for this to be a comment, but no reputation)