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sky(phase-8.1): CLAMP_TO_EDGE on static sky meshes

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The dome is 5 flat quads meeting at edges. Under GL_REPEAT + LINEAR
filtering, the edge pixels of each wall wrap-sample to the OPPOSITE
edge of the SAME texture (repeat wraps 1.0→0.0). Those opposite-edge
pixels never match the adjacent wall's border, so every dome seam
showed up as a visible line — four vertical wall lines plus the top
cap formed a huge cube-outline in the sky.

Switch to GL_CLAMP_TO_EDGE for any sky submesh whose SkyObject has
TexVelocityX == TexVelocityY == 0 (i.e. not a scrolling cloud layer).
Scrolling clouds keep GL_REPEAT because their UV-offset accumulates
and needs seamless wrap. One-line heuristic on TexVelocity picks the
mode per-object per draw.

User confirmed both the cube-edges artifact and the "huge square in
the sky" artifact are gone after this change. Both were the same bug
— the square was the four wall seams forming a closed rectangle
across the view.
This commit is contained in:
Erik 2026-04-24 20:42:59 +02:00
parent 1d54880213
commit 593b76fda1
1 changed files with 17 additions and 0 deletions
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17
src/AcDream.App/Rendering/Sky/SkyRenderer.cs
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@ -221,6 +221,23 @@ public sealed unsafe class SkyRenderer : IDisposable
uint tex = _textures.GetOrUpload(sub.SurfaceId);
_gl.ActiveTexture(TextureUnit.Texture0);
_gl.BindTexture(TextureTarget.Texture2D, tex);
// Sky meshes need per-object wrap mode. The dome is 5 flat
// walls meeting at edges — under GL_REPEAT any UV drift
// past [0,1] wraps to the opposite edge of the texture,
// drawing a visible line along each wall seam. Static
// sky GfxObjs (dome, sun, moon, stars) should use
// CLAMP_TO_EDGE to avoid that bleed. Scrolling cloud
// layers (TexVelocity != 0) still need REPEAT so the
// animated UV offset wraps correctly. Detection heuristic:
// non-zero TexVelocity on either axis ⇒ scrolling layer.
bool scrolling = obj.TexVelocityX != 0f || obj.TexVelocityY != 0f;
int wrapMode = scrolling
? (int)TextureWrapMode.Repeat
: (int)TextureWrapMode.ClampToEdge;
_gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, wrapMode);
_gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, wrapMode);
_gl.BindVertexArray(sub.Vao);
_gl.DrawElements(PrimitiveType.Triangles,
(uint)sub.IndexCount,