wip: Ray mapping

2026-05-31 01:11:58 +02:00
parent aa82cacd5c
commit d63ef70e48
3 changed files with 752 additions and 68 deletions
@@ -1,16 +1,74 @@
-void Facing_float(float3 ObjectPos, float3 Origin, float3 InUp, uint Orthographic, out float3 FacingWorldPos, out float3 FacingObjectPos, out float3 Right, out float3 Up, out float3 Forward)
+#include "Assets/_Content/Shaders/Include/Noises.hlsl"
+
+float2 WorldToScreenUV(float3 posWS)
 {
-    float3 origin = TransformObjectToWorld(float3(0, 0, 0));
-    float3 view = lerp(normalize(origin - _WorldSpaceCameraPos.xyz), GetViewForwardDir(), Orthographic);
-    
-    Up = normalize(InUp);
-    Right = normalize(cross(Up, view));
-    Forward = cross(Right, Up);
-    
-    FacingWorldPos = Origin;
-    FacingWorldPos += ObjectPos.x * length(TransformObjectToWorld(float3(1, 0, 0)) - origin) * Right;
-    FacingWorldPos += ObjectPos.y * length(TransformObjectToWorld(float3(0, 1, 0)) - origin) * Up;
-    FacingWorldPos += ObjectPos.z * length(TransformObjectToWorld(float3(0, 0, 1)) - origin) * Forward;
-    
-    FacingObjectPos = TransformWorldToObject(FacingWorldPos);
+    float4 clip = TransformWorldToHClip(posWS);
+    float2 ndc = clip.xy / clip.w; // [-1, 1]
+    return ndc * .5 + .5; // [0, 1]
 }
+
+float3 GetBillboardPositionWS(float3 PositionOS, float3 PivotWS, float3 ViewDirWS)
+{
+    float3 upWS = normalize(TransformObjectToWorldDir(float3(0, 1, 0)));
+
+    float3 rightWS = cross(upWS, ViewDirWS);
+
+    if (dot(rightWS, rightWS) < 1e-5)
+        rightWS = normalize(TransformObjectToWorldDir(float3(1, 0, 0)));
+    else
+        rightWS = normalize(rightWS);
+
+    float3 forwardWS = normalize(cross(rightWS, upWS));
+
+    return PivotWS + PositionOS.x * rightWS + PositionOS.y * upWS + PositionOS.z * forwardWS;
+}
+
+float3 ApplayerTaperAndScale(float3 PositionOS, float3 Scale)
+{
+    float taper = lerp(Scale.z, 1, saturate(PositionOS.y));
+
+    float3 p = PositionOS;
+    p.xy *= Scale.xy;
+    p.x *= taper;
+
+    return p;
+}
+
+void Ray_float
+(
+    float3 Color,
+    float3 PositionOS,
+    float4 ScreenPos,
+    uint Orthographic,
+    out float3 OutPosition,
+    out float3 OutColor
+)
+{
+    float3 pivot = TransformObjectToWorld(float3(0, 0, 0));
+
+    float3 scale = float3
+    (
+        length(TransformObjectToWorld(float3(1, 0, 0)) - pivot),
+        length(TransformObjectToWorld(float3(0, 1, 0)) - pivot),
+        length(TransformObjectToWorld(float3(0, 0, 1)) - pivot)
+    );
+
+    float3 viewDir = lerp(normalize(pivot - _WorldSpaceCameraPos.xyz), GetViewForwardDir(), Orthographic);
+
+    float3 pOS_0 = ApplayerTaperAndScale(PositionOS, scale);
+    float3 pOS_1 = ApplayerTaperAndScale(float3( .5, PositionOS.y, 0), scale);
+    float3 pOS_2 = ApplayerTaperAndScale(float3(-.5, PositionOS.y, 0), scale);
+              
+    float3 pWS_0 = GetBillboardPositionWS(pOS_0, pivot, viewDir);
+    float3 pWS_1 = GetBillboardPositionWS(pOS_1, pivot, viewDir);
+    float3 pWS_2 = GetBillboardPositionWS(pOS_2, pivot, viewDir);
+
+    float2 pSC_0 = ScreenPos.xy;
+    float2 pSC_1 = WorldToScreenUV(pWS_1);
+    float2 pSC_2 = WorldToScreenUV(pWS_2);
+    
+    float2 uv = float2(distance(pSC_0.x, pSC_2.x) / distance(pSC_1.x, pSC_2.x), pOS_0.y / scale.y);
+    
+    OutPosition = TransformWorldToObject(pWS_0);
+    OutColor = float3(uv, 0);
+}