Compress baked PNGs and tighten XPbr shadows with URP quality tweaks.

Add png_compress to the model pipeline and update TownSquare lighting plus MaleExplorer/plaza textures.

Co-authored-by: Cursor <cursoragent@cursor.com>

AIClient/AgentScripts/BuildTownSquare.cs

@@ -310,8 +310,9 @@ public static class BuildTownSquare
         var light = lightGo.AddComponent<Light>();
         light.type = LightType.Directional;
         light.color = new Color(1f, 0.96f, 0.88f);
-        light.intensity = 1.05f;
+        light.intensity = 1.15f;
         light.shadows = LightShadows.Soft;
+        light.shadowStrength = 1f;
         lightGo.transform.rotation = Quaternion.Euler(50f, -30f, 0f);
 
         var camGo = new GameObject("Main Camera");
@@ -330,9 +331,9 @@ public static class BuildTownSquare
         PrefabUtility.InstantiatePrefab(plaza);
 
         RenderSettings.ambientMode = AmbientMode.Trilight;
-        RenderSettings.ambientSkyColor = new Color(0.55f, 0.7f, 0.85f);
-        RenderSettings.ambientEquatorColor = new Color(0.5f, 0.52f, 0.48f);
-        RenderSettings.ambientGroundColor = new Color(0.35f, 0.32f, 0.28f);
+        RenderSettings.ambientSkyColor = new Color(0.32f, 0.40f, 0.50f);
+        RenderSettings.ambientEquatorColor = new Color(0.24f, 0.26f, 0.24f);
+        RenderSettings.ambientGroundColor = new Color(0.16f, 0.15f, 0.13f);
 
         EditorSceneManager.SaveScene(scene, ScenePath);
         return ScenePath;

AIClient/Assets/Bundles/Scenes/Town/TownSquare/TownSquare.unity

@@ -20,9 +20,9 @@ RenderSettings:
   m_FogDensity: 0.01
   m_LinearFogStart: 0
   m_LinearFogEnd: 300
-  m_AmbientSkyColor: {r: 0.55, g: 0.7, b: 0.85, a: 1}
-  m_AmbientEquatorColor: {r: 0.5, g: 0.52, b: 0.48, a: 1}
-  m_AmbientGroundColor: {r: 0.35, g: 0.32, b: 0.28, a: 1}
+  m_AmbientSkyColor: {r: 0.32, g: 0.4, b: 0.5, a: 1}
+  m_AmbientEquatorColor: {r: 0.24, g: 0.26, b: 0.24, a: 1}
+  m_AmbientGroundColor: {r: 0.16, g: 0.15, b: 0.13, a: 1}
   m_AmbientIntensity: 1
   m_AmbientMode: 1
   m_SubtractiveShadowColor: {r: 0.42, g: 0.478, b: 0.627, a: 1}
@@ -281,6 +281,7 @@ GameObject:
   m_Component:
   - component: {fileID: 2073245442}
   - component: {fileID: 2073245441}
+  - component: {fileID: 2073245443}
   m_Layer: 0
   m_Name: Directional Light
   m_TagString: Untagged
@@ -300,7 +301,7 @@ Light:
   m_Type: 1
   m_Shape: 0
   m_Color: {r: 1, g: 0.96, b: 0.88, a: 1}
-  m_Intensity: 1.05
+  m_Intensity: 1.15
   m_Range: 10
   m_SpotAngle: 30
   m_InnerSpotAngle: 21.80208
@@ -365,6 +366,29 @@ Transform:
   m_Children: []
   m_Father: {fileID: 0}
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!114 &2073245443
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 2073245440}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 474bcb49853aa07438625e644c072ee6, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  m_Version: 3
+  m_UsePipelineSettings: 1
+  m_AdditionalLightsShadowResolutionTier: 2
+  m_LightLayerMask: 1
+  m_RenderingLayers: 1
+  m_CustomShadowLayers: 0
+  m_ShadowLayerMask: 1
+  m_ShadowRenderingLayers: 1
+  m_LightCookieSize: {x: 1, y: 1}
+  m_LightCookieOffset: {x: 0, y: 0}
+  m_SoftShadowQuality: 0
 --- !u!1660057539 &9223372036854775807
 SceneRoots:
   m_ObjectHideFlags: 0

AIClient/Assets/Bundles/Shaders/XShader/XPbr.shader

@@ -13,6 +13,10 @@ Shader "Test/XPbr"
 		_Metallic("Metallic", Range(0.0, 1.0)) = 0.8
 		_Roughness("Roughness", Range(0.0, 1.0)) = 0.6
 		_AO("AO", Range(0.0, 1.0)) = 1.0
+
+		[HideInInspector][NoScaleOffset]unity_Lightmaps("unity_Lightmaps", 2DArray) = "" {}
+		[HideInInspector][NoScaleOffset]unity_LightmapsInd("unity_LightmapsInd", 2DArray) = "" {}
+		[HideInInspector][NoScaleOffset]unity_ShadowMasks("unity_ShadowMasks", 2DArray) = "" {}
 	}
 
 	SubShader
@@ -33,13 +37,16 @@ Shader "Test/XPbr"
 			#pragma target 2.0
 
 			#pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
-            #pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
+			#pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
+			#pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS
+			#pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
+
+			#pragma multi_compile _ LIGHTMAP_SHADOW_MIXING
+			#pragma multi_compile _ SHADOWS_SHADOWMASK
+			#pragma multi_compile _ DIRLIGHTMAP_COMBINED
 			#pragma multi_compile _ LIGHTMAP_ON
 			#pragma multi_compile _ DYNAMICLIGHTMAP_ON
 
-			#pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS
-            #pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
-
 			#pragma shader_feature_local_fragment _ALPHATEST_ON
 
 			#pragma vertex vert
@@ -155,18 +162,13 @@ Shader "Test/XPbr"
 			ColorMask 0
 
 			HLSLPROGRAM
-			// Required to compile gles 2.0 with standard srp library
 			#pragma prefer_hlslcc gles
 			#pragma exclude_renderers d3d11_9x
 			#pragma target 2.0
 
-			// -------------------------------------
-			// Material Keywords
 			#pragma shader_feature_local_fragment _ALPHATEST_ON
-
-			//--------------------------------------
-			// GPU Instancing
 			#pragma multi_compile_instancing
+			#pragma multi_compile_vertex _ _CASTING_PUNCTUAL_LIGHT_SHADOW
 
 			#pragma vertex vert
 			#pragma fragment frag
@@ -175,6 +177,7 @@ Shader "Test/XPbr"
 			#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl"
 
 			float3 _LightDirection;
+			float3 _LightPosition;
 
 			Varyings vert(Attributes input)
 			{
@@ -185,13 +188,18 @@ Shader "Test/XPbr"
 
 				float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
 				float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
+			#if defined(_CASTING_PUNCTUAL_LIGHT_SHADOW)
+				float3 lightDirectionWS = normalize(_LightPosition - positionWS);
+			#else
+				float3 lightDirectionWS = _LightDirection;
+			#endif
 
-				float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, _LightDirection));
+				float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, lightDirectionWS));
 
 				#if UNITY_REVERSED_Z
-					positionCS.z = min(positionCS.z, positionCS.w * UNITY_NEAR_CLIP_VALUE);
+					positionCS.z = min(positionCS.z, UNITY_NEAR_CLIP_VALUE);
 				#else
-					positionCS.z = max(positionCS.z, positionCS.w * UNITY_NEAR_CLIP_VALUE);
+					positionCS.z = max(positionCS.z, UNITY_NEAR_CLIP_VALUE);
 				#endif
 
 				output.positionCS = positionCS;
@@ -210,6 +218,136 @@ Shader "Test/XPbr"
 			}
 			ENDHLSL
 		}
+
+		Pass
+		{
+			Name "DepthOnly"
+			Tags{ "LightMode" = "DepthOnly" }
+
+			ZWrite On
+			ColorMask R
+
+			HLSLPROGRAM
+			#pragma prefer_hlslcc gles
+			#pragma exclude_renderers d3d11_9x
+			#pragma target 2.0
+
+			#pragma shader_feature_local_fragment _ALPHATEST_ON
+			#pragma multi_compile_instancing
+
+			#pragma vertex vert
+			#pragma fragment frag
+
+			#include "XPbr_Base.hlsl"
+
+			Varyings vert(Attributes input)
+			{
+				Varyings output = (Varyings)0;
+				UNITY_SETUP_INSTANCE_ID(input);
+				UNITY_TRANSFER_INSTANCE_ID(input, output);
+				UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output);
+
+				output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
+				output.uv = TRANSFORM_TEX(input.texcoord, _MainTex);
+				return output;
+			}
+
+			half frag(Varyings input) : SV_TARGET
+			{
+			#if defined(_ALPHATEST_ON)
+				half alpha = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv).a;
+				clip(alpha - _Cutoff);
+			#endif
+				return input.positionCS.z;
+			}
+			ENDHLSL
+		}
+
+		Pass
+		{
+			Name "Meta"
+			Tags{ "LightMode" = "Meta" }
+
+			Cull Off
+
+			HLSLPROGRAM
+			#pragma target 2.0
+			#pragma vertex vert
+			#pragma fragment frag
+			#pragma shader_feature_local_fragment _ALPHATEST_ON
+			#pragma shader_feature EDITOR_VISUALIZATION
+
+			#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
+			#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/MetaInput.hlsl"
+
+			CBUFFER_START(UnityPerMaterial)
+			float4	_MainTex_ST;
+			half4	_BaseColor;
+			half	_Cutoff;
+			half	_Metallic;
+			half	_Roughness;
+			half	_AO;
+			CBUFFER_END
+			TEXTURE2D(_MainTex);    SAMPLER(sampler_MainTex);
+			TEXTURE2D(_MixTex);     SAMPLER(sampler_MixTex);
+
+			struct MetaAttributes
+			{
+				float4 positionOS   : POSITION;
+				float3 normalOS     : NORMAL;
+				float2 uv0          : TEXCOORD0;
+				float2 uv1          : TEXCOORD1;
+				float2 uv2          : TEXCOORD2;
+				UNITY_VERTEX_INPUT_INSTANCE_ID
+			};
+
+			struct MetaVaryings
+			{
+				float4 positionCS   : SV_POSITION;
+				float2 uv           : TEXCOORD0;
+			#ifdef EDITOR_VISUALIZATION
+				float2 VizUV        : TEXCOORD1;
+				float4 LightCoord   : TEXCOORD2;
+			#endif
+			};
+
+			MetaVaryings vert(MetaAttributes input)
+			{
+				MetaVaryings output = (MetaVaryings)0;
+				output.positionCS = UnityMetaVertexPosition(input.positionOS.xyz, input.uv1, input.uv2);
+				output.uv = TRANSFORM_TEX(input.uv0, _MainTex);
+			#ifdef EDITOR_VISUALIZATION
+				UnityEditorVizData(input.positionOS.xyz, input.uv0, input.uv1, input.uv2, output.VizUV, output.LightCoord);
+			#endif
+				return output;
+			}
+
+			half4 frag(MetaVaryings input) : SV_Target
+			{
+				half4 albedoAlpha = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
+			#if defined(_ALPHATEST_ON)
+				clip(albedoAlpha.a - _Cutoff);
+			#endif
+				half4 mixTex = SAMPLE_TEXTURE2D(_MixTex, sampler_MixTex, input.uv);
+				half3 albedo = albedoAlpha.rgb * _BaseColor.rgb;
+				half metallic = saturate(mixTex.b * _Metallic);
+				half smoothness = 1.0 - saturate(mixTex.a * _Roughness);
+				half alpha = 1.0;
+
+				BRDFData brdfData;
+				InitializeBRDFData(albedo, metallic, half3(0.0, 0.0, 0.0), smoothness, alpha, brdfData);
+
+				MetaInput metaInput;
+				metaInput.Albedo = brdfData.diffuse + brdfData.specular * brdfData.roughness * 0.5;
+				metaInput.Emission = half3(0.0, 0.0, 0.0);
+			#ifdef EDITOR_VISUALIZATION
+				metaInput.VizUV = input.VizUV;
+				metaInput.LightCoord = input.LightCoord;
+			#endif
+				return UnityMetaFragment(metaInput);
+			}
+			ENDHLSL
+		}
 	}
 
 	FallBack Off

AIClient/Assets/Bundles/Shaders/XShader/XPbr_Base.hlsl

@@ -121,11 +121,10 @@ void InitializeInputData(Varyings input, half3 normalTS, out InputData inputData
     inputData.bakedGI = SAMPLE_GI(input.staticLightmapUV, input.vertexSH, inputData.normalWS);
 #else
     inputData.bakedGI = SampleSH(inputData.normalWS);
-#endif
-    // 仅在运行时全局环境光开启后才覆盖（Game.cs 设置）；否则保留场景自身 SH/光照贴图，
-    // 避免编辑器预览比 URP Lit 亮（旧写法无条件覆盖成硬编码的高强度三色环境光）
+    // 仅覆盖动态物体的探针环境光。光照贴图（含烘焙阴影/间接光）必须保留。
     if (_XRuntimeAmbientEnabled > 0.5h)
         inputData.bakedGI = SampleXRuntimeAmbient(inputData.normalWS);
+#endif
 
     inputData.normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(input.positionCS);
     inputData.shadowMask = SAMPLE_SHADOWMASK(input.staticLightmapUV);

AIClient/Assets/Settings/URP/UniversalRP-1LowQuality.asset

@@ -34,7 +34,7 @@ MonoBehaviour:
   m_LODCrossFadeDitheringType: 1
   m_ShEvalMode: 0
   m_MainLightRenderingMode: 1
-  m_MainLightShadowsSupported: 0
+  m_MainLightShadowsSupported: 1
   m_MainLightShadowmapResolution: 1024
   m_AdditionalLightsRenderingMode: 1
   m_AdditionalLightsPerObjectLimit: 2
@@ -45,7 +45,7 @@ MonoBehaviour:
   m_AdditionalLightsShadowResolutionTierHigh: 1024
   m_ReflectionProbeBlending: 0
   m_ReflectionProbeBoxProjection: 0
-  m_ShadowDistance: 10
+  m_ShadowDistance: 150
   m_ShadowCascadeCount: 1
   m_Cascade2Split: 0.16666667
   m_Cascade3Split: {x: 0.25800002, y: 0.5776}

AIClient/Assets/Settings/URP/UniversalRP-2MediumQuality.asset

@@ -34,8 +34,8 @@ MonoBehaviour:
   m_LODCrossFadeDitheringType: 1
   m_ShEvalMode: 0
   m_MainLightRenderingMode: 1
-  m_MainLightShadowsSupported: 0
-  m_MainLightShadowmapResolution: 512
+  m_MainLightShadowsSupported: 1
+  m_MainLightShadowmapResolution: 1024
   m_AdditionalLightsRenderingMode: 1
   m_AdditionalLightsPerObjectLimit: 4
   m_AdditionalLightShadowsSupported: 0
@@ -45,7 +45,7 @@ MonoBehaviour:
   m_AdditionalLightsShadowResolutionTierHigh: 1024
   m_ReflectionProbeBlending: 0
   m_ReflectionProbeBoxProjection: 0
-  m_ShadowDistance: 15
+  m_ShadowDistance: 150
   m_ShadowCascadeCount: 1
   m_Cascade2Split: 0.16666667
   m_Cascade3Split: {x: 0.25800002, y: 0.5776}

AIClient/Assets/Settings/URP/UniversalRP-3HighQuality.asset

@@ -35,7 +35,7 @@ MonoBehaviour:
   m_ShEvalMode: 0
   m_MainLightRenderingMode: 1
   m_MainLightShadowsSupported: 1
-  m_MainLightShadowmapResolution: 1024
+  m_MainLightShadowmapResolution: 2048
   m_AdditionalLightsRenderingMode: 1
   m_AdditionalLightsPerObjectLimit: 4
   m_AdditionalLightShadowsSupported: 0
@@ -45,7 +45,7 @@ MonoBehaviour:
   m_AdditionalLightsShadowResolutionTierHigh: 1024
   m_ReflectionProbeBlending: 0
   m_ReflectionProbeBoxProjection: 0
-  m_ShadowDistance: 15
+  m_ShadowDistance: 150
   m_ShadowCascadeCount: 2
   m_Cascade2Split: 0.26666668
   m_Cascade3Split: {x: 0.25800002, y: 0.5776}

AIClient/Assets/Settings/URP/UniversalRP-4VeryHighQuality.asset

@@ -45,7 +45,7 @@ MonoBehaviour:
   m_AdditionalLightsShadowResolutionTierHigh: 1024
   m_ReflectionProbeBlending: 0
   m_ReflectionProbeBoxProjection: 0
-  m_ShadowDistance: 30
+  m_ShadowDistance: 150
   m_ShadowCascadeCount: 2
   m_Cascade2Split: 0.2
   m_Cascade3Split: {x: 0.10000001, y: 0.3}

GameResProductProc.md

@@ -267,6 +267,7 @@ python Tools/gpt_image_generate.py --result-only --quality high --aspect-ratio 1
 - 角色安装可参考：`Tools/install_character_bundles.py`。场景分件：拷到 `Bundles/Scenes/{类型}/{场景号}/{英文短名}/`（`Tools/output/run_townsquare_pipeline.py`）。设计原稿不进 Bundles。
 - 碎叶等非流形：`bl_decimate.py` 在 collapse 卡住后会体素重网格再减面。
 - 轴向：混元 GLB = glTF Y-up。烘焙在 Blender 里用 Z-up；**导出 FBX 时** `prepare_game_export` 转回 Y-up，原点放在**底面中点**。**局部 -Z 是正面**（设计图朝相机的那面，与 glTF 相机看向 -Z 一致）。Unity 摆放用「-Z 指向目标」，不要用 `LookRotation` 默认的 +Z forward，也不要再绕 X 扶正或抬高度。
+- 最终 `_base.png` / `_mix.png`（以及烘焙五通道 PNG）写出时做 **PNG 无损压缩**（zlib 最高档；有 Pillow 则 `optimize=True`）。像素不变，只缩小文件。
 - 角色 Prefab：Unity 菜单 `AIGame/M3/Setup Character Prefab`。其他类型的 Prefab 步骤在细化时写明。
 
 ---

ResourceCreate.md

@@ -97,6 +97,7 @@ python Tools/hunyuan_3d_generate.py -i ref.png -o out.glb --no-interactive-login
   -> model_translator（默认）-> XPbr 两张图 + .mat/.meta
        <名>_base.png  RGB=Albedo A=AO/透明
        <名>_mix.png   RG=球面法线 B=Metallic A=Roughness
+       写出 PNG 时无损压缩（Blender compression=100 + zlib 9 / Pillow optimize）
 ```
 
 ### AI / 命令行调用

Tools/model_tools/README.md

@@ -9,6 +9,7 @@
   -> model_translator：打包为 XPbr 两张图 + .mat/.meta
        _base.png  RGB=Albedo  A=AO/透明
        _mix.png   RG=球面法线  B=Metallic  A=Roughness
+       写出时 PNG 无损压缩（体积更小，像素不变）
 ```
 
 ## 环境

Tools/model_tools/bl_bake.py

@@ -7,6 +7,7 @@ import os
 import sys
 
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+from png_compress import compress_png, prepare_blender_png
 
 DEFAULT_RAY_PCT = 0.02   # 测量失败时回退：低模包围盒对角线 * 2%
 RAY_SAFETY = 1.5        # 自适应射线安全系数（分离 P99 × 此值）
@@ -199,8 +200,10 @@ def _bake_pass(low, high, target_node, name, bake_type, size, colorspace,
     path = os.path.abspath(os.path.join(outdir, "%s_%s.png" % (stem, name)))
     img.filepath_raw = path
     img.file_format = 'PNG'
+    prepare_blender_png(100)
     img.save()
     bpy.data.images.remove(img)
+    compress_png(path)
     return os.path.basename(path)
 
 

Tools/model_tools/bl_convert.py

@@ -9,6 +9,7 @@ import numpy as np
 
 # blender --python 不会把脚本目录加入 sys.path，手动加入以复用 unity_assets（纯 stdlib）
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+from png_compress import compress_png, prepare_blender_png
 from unity_assets import safe_name
 
 AO_NAME_RE = re.compile(r"(ao|occlusion|ambient)", re.I)
@@ -269,8 +270,10 @@ def _save_png(path, rgba):
     img.filepath_raw = path
     img.file_format = 'PNG'
     img.alpha_mode = 'CHANNEL_PACKED'
+    prepare_blender_png(100)
     img.save()
     bpy.data.images.remove(img)
+    compress_png(path)
 
 
 def _convert_material(mat, model_name, outdir, max_size, used_snames, src_dir):

Tools/model_tools/model_bake.py

@@ -8,6 +8,7 @@ import os
 from bl_bake import output_stem
 from bl_decimate import model_format
 from mt_run import HERE, find_blender, run_blender_script
+from png_compress import compress_pngs
 
 
 def main():
@@ -38,6 +39,9 @@ def main():
                            [args.high, args.low, outdir, str(args.size),
                             ray, str(args.samples)],
                            blender_args=("-t", "1"))
+    compress_pngs(
+        os.path.join(outdir, fname) for fname in (s.get("outputs") or {}).values()
+    )
     print("== %s（高 %d 面 / 低 %d 面，射线距离 %.4f）-> %s" %
           (s["stem"], s["high_tris"], s["low_tris"], s["ray_distance"], outdir))
     for name, fname in s["outputs"].items():

Tools/model_tools/model_lowpoly_bake.py

@@ -28,6 +28,7 @@ if str(_HERE) not in sys.path:
 from bl_bake import output_stem  # noqa: E402
 from bl_decimate import model_format  # noqa: E402
 from mt_run import find_blender, run_blender_script  # noqa: E402
+from png_compress import compress_pngs  # noqa: E402
 
 
 def _now_iso() -> str:
@@ -211,6 +212,9 @@ def run_pipeline(
         ],
         blender_args=("-t", "1"),
     )
+    compress_pngs(
+        str(bake_dir / fname) for fname in (bake.get("outputs") or {}).values()
+    )
 
     xpbr_dir = None
     xpbr_summary = None

Tools/model_tools/model_translator.py

@@ -8,6 +8,7 @@ import sys
 
 import unity_assets as ua
 from mt_run import HERE, find_blender, run_blender_script
+from png_compress import compress_dir_pngs
 
 
 def write_unity_assets(outdir, summary, max_size):
@@ -79,6 +80,7 @@ def translate_fbx(src, outdir, max_size=2048, blender=None):
     summary = run_blender_script(
         blender_exe, "bl_convert.py", [src, outdir, str(max_size)]
     )
+    compress_dir_pngs(outdir, suffixes=("_base.png", "_mix.png"))
     unity = write_unity_assets(outdir, summary, max_size)
     return {**summary, "unity": unity}
 

Tools/model_tools/png_compress.py

@@ -0,0 +1,139 @@
+"""Lossless PNG size reduction for bake outputs.
+
+Blender's default PNG compression is low (~15/100). Final _base/_mix (and
+bake maps) are rewritten with zlib level 9. Pillow `optimize=True` is used
+when available (system Python); Blender's interpreter falls back to IDAT
+recompress via stdlib only. Pixels are unchanged.
+"""
+from __future__ import annotations
+
+import os
+import struct
+import zlib
+from typing import Dict, Iterable, List, Optional
+
+PNG_SIG = b"\x89PNG\r\n\x1a\n"
+
+
+def prepare_blender_png(compression: int = 100) -> None:
+    """Blender Image.save() uses scene render PNG compression (0-100)."""
+    import bpy
+
+    settings = bpy.context.scene.render.image_settings
+    settings.file_format = "PNG"
+    settings.color_depth = "8"
+    settings.compression = int(compression)
+
+
+def compress_png(path: str, level: int = 9) -> Dict[str, int]:
+    """Rewrite `path` in place. Returns {before, after} byte sizes."""
+    path = os.path.abspath(path)
+    before = os.path.getsize(path)
+    after = before
+    tmp = path + ".pngcompress.tmp"
+    try:
+        if _compress_with_pillow(path, tmp, level) or _compress_idat(path, tmp, level):
+            new_size = os.path.getsize(tmp)
+            if new_size < before:
+                os.replace(tmp, path)
+                after = new_size
+            elif os.path.isfile(tmp):
+                os.remove(tmp)
+    finally:
+        if os.path.isfile(tmp):
+            try:
+                os.remove(tmp)
+            except OSError:
+                pass
+    return {"before": before, "after": after}
+
+
+def compress_pngs(paths: Iterable[str], level: int = 9) -> List[Dict[str, object]]:
+    reports = []
+    for path in paths:
+        if not path or not os.path.isfile(path):
+            continue
+        if os.path.splitext(path)[1].lower() != ".png":
+            continue
+        sizes = compress_png(path, level=level)
+        reports.append({"path": os.path.abspath(path), **sizes})
+    return reports
+
+
+def compress_dir_pngs(directory: str, suffixes: Optional[Iterable[str]] = None) -> List[Dict[str, object]]:
+    """Compress PNGs in a directory. `suffixes` like ('_base.png', '_mix.png')."""
+    directory = os.path.abspath(directory)
+    names = sorted(os.listdir(directory)) if os.path.isdir(directory) else []
+    suffix_tuple = tuple(suffixes) if suffixes else None
+    paths = []
+    for name in names:
+        if not name.lower().endswith(".png"):
+            continue
+        if suffix_tuple and not name.endswith(suffix_tuple):
+            continue
+        paths.append(os.path.join(directory, name))
+    return compress_pngs(paths)
+
+
+def _compress_with_pillow(src: str, dst: str, level: int) -> bool:
+    try:
+        from PIL import Image
+    except ImportError:
+        return False
+    try:
+        with Image.open(src) as im:
+            im.load()
+            im.save(dst, format="PNG", optimize=True, compress_level=level)
+    except Exception:
+        return False
+    return os.path.isfile(dst)
+
+
+def _write_chunk(buf: bytearray, ctype: bytes, data: bytes) -> None:
+    buf.extend(struct.pack(">I", len(data)))
+    buf.extend(ctype)
+    buf.extend(data)
+    buf.extend(struct.pack(">I", zlib.crc32(ctype + data) & 0xFFFFFFFF))
+
+
+def _compress_idat(src: str, dst: str, level: int) -> bool:
+    with open(src, "rb") as f:
+        data = f.read()
+    if len(data) < 8 or data[:8] != PNG_SIG:
+        return False
+    pos = 8
+    before_idat: List[tuple] = []
+    after_idat: List[tuple] = []
+    idat_parts: List[bytes] = []
+    seen_idat = False
+    while pos + 12 <= len(data):
+        length = struct.unpack(">I", data[pos : pos + 4])[0]
+        ctype = data[pos + 4 : pos + 8]
+        end = pos + 8 + length
+        if end + 4 > len(data):
+            return False
+        cdata = data[pos + 8 : end]
+        pos = end + 4
+        if ctype == b"IDAT":
+            idat_parts.append(cdata)
+            seen_idat = True
+            continue
+        if seen_idat:
+            after_idat.append((ctype, cdata))
+        else:
+            before_idat.append((ctype, cdata))
+        if ctype == b"IEND":
+            break
+    if not idat_parts:
+        return False
+    raw = zlib.decompress(b"".join(idat_parts))
+    packed = zlib.compress(raw, level)
+    out = bytearray(PNG_SIG)
+    for ctype, cdata in before_idat:
+        _write_chunk(out, ctype, cdata)
+    _write_chunk(out, b"IDAT", packed)
+    for ctype, cdata in after_idat:
+        _write_chunk(out, ctype, cdata)
+    with open(dst, "wb") as f:
+        f.write(out)
+    return True

Tools/model_tools/tests/test_png_compress.py

@@ -0,0 +1,31 @@
+import os
+import sys
+import tempfile
+import unittest
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from png_compress import compress_png
+
+
+class CompressPngTests(unittest.TestCase):
+    def test_pixels_unchanged_and_smaller(self):
+        from PIL import Image
+
+        w = h = 64
+        pixels = [(40, 80, 120, 255)] * (w * h)
+        with tempfile.TemporaryDirectory() as d:
+            path = os.path.join(d, "a.png")
+            im = Image.new("RGBA", (w, h))
+            im.putdata(pixels)
+            im.save(path, format="PNG", compress_level=0, optimize=False)
+            before = os.path.getsize(path)
+            src_bytes = list(Image.open(path).getdata())
+            sizes = compress_png(path)
+            after_im = Image.open(path)
+            self.assertEqual(list(after_im.getdata()), src_bytes)
+            self.assertLess(sizes["after"], before)
+            self.assertEqual(sizes["before"], before)
+
+
+if __name__ == "__main__":
+    unittest.main()