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fix(lighting): port ACME lighting constants replacing guessed values

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Replace guessed sun direction (0.5, 0.4, 0.6) with ACME's verified
value (0.5, 0.3, -0.3) from GameScene.cs:238. Replace hardcoded
ambient/diffuse (0.25/0.75) with ACME's ambient intensity 0.45 from
LandscapeEditorSettings.cs:108.

Terrain shaders now match ACME Landscape.vert/frag pattern:
- Vertex shader computes Lambert term with xLightDirection uniform
- Fragment shader applies: color * (clamp(lambert, 0, 1) + xAmbient)

Static object shader matches ACME StaticObject.vert:
- LightingFactor = max(dot(N, -L), 0) + ambient
- Removed separate uDiffuseIntensity (ACME doesn't have one)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-04-13 22:01:28 +02:00
parent 1b3387f991
commit 31d3a4678f
5 changed files with 31 additions and 27 deletions
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16
src/AcDream.App/Rendering/Shaders/terrain.frag
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@ -6,6 +6,7 @@
in vec2 vBaseUV;
in vec3 vWorldNormal;
in float vLightingFactor;
in vec4 vOverlay0;
in vec4 vOverlay1;
in vec4 vOverlay2;
@ -17,11 +18,7 @@ out vec4 fragColor;
uniform sampler2DArray uTerrain; // 33+ layers — TerrainAtlas.GlTexture
uniform sampler2DArray uAlpha; // 8+ layers — TerrainAtlas.GlAlphaTexture
// Phase 3a lighting (in sync with mesh.frag — update both together).
const vec3 SUN_DIR = normalize(vec3(0.5, 0.4, 0.6));
const float AMBIENT = 0.25;
const float DIFFUSE = 0.75;
uniform float xAmbient; // ambient intensity (matching ACME Landscape.frag)
// Per-texture tiling repeat count across a cell. WorldBuilder uses
// uTexTiling[36] uploaded from the dats; we default to 1.0 (one tile per
@ -118,10 +115,9 @@ void main() {
vec3 roadMasked = roads.rgb * roads.a;
vec3 rgb = clamp(baseMasked + ovlMasked + roadMasked, 0.0, 1.0);
// Phase 3a/3b directional lighting (in sync with mesh.frag constants).
vec3 N = normalize(vWorldNormal);
float ndotl = max(dot(N, SUN_DIR), 0.0);
float lighting = AMBIENT + DIFFUSE * ndotl;
// Lighting matching ACME Landscape.frag:
// litColor = finalColor * (saturate(vLightingFactor) + xAmbient);
vec3 litColor = rgb * (clamp(vLightingFactor, 0.0, 1.0) + xAmbient);
fragColor = vec4(rgb * lighting, 1.0);
fragColor = vec4(litColor, 1.0);
}