some ray marching

1 files changed, 81 insertions, 7 deletions

diff --git a/ray_marching.cginc b/ray_marching.cginc
index 69f6438..e5ae03d 100644
--- a/ray_marching.cginc
+++ b/ray_marching.cginc
@@ -1,35 +1,109 @@
 #ifndef __RAY_MARCHING_INC
 #define __RAY_MARCHING_INC
 
+#include "math.cginc"
+#include "ray_marching_maps.hlsl"
+#include "texture_utils.cginc"
+
 struct RayMarchResult {
   float3 objPos;
   float3 objNorm;
+  float3 objTan;
 };
 
+float3 getObjPos(v2f i)
+{
+#if defined(_VERTEX_DEFORMATION_FRAGMENT_NORMALS) || defined(_VERTEX_DEFORMATION_TESSELLATION)
+  return i.objPos_orig;
+#else
+  return i.objPos;
+#endif
+}
+
+#if defined(_RAY_MARCHING_BAKED_ORIGINS)
 float3 GetFragToOrigin(v2f i) {
   return (i.color * 2.0f - 1.0f) / i.color.a;
 }
-
 float4 GetRotation(v2f i, float2 uv_channels) {
   float4 quat;
   quat.xy = get_uv_by_channel(i, uv_channels.x);
   quat.zw = get_uv_by_channel(i, uv_channels.y);
   return quat;
 }
-
-RayMarchResult march_c31_00(v2f i) {
+void GetRoRd(v2f i, out float3 ro, out float3 rd) {
   float3 obj_space_camera_pos = mul(unity_WorldToObject, float4(_WorldSpaceCameraPos, 1.0));
   float3 frag_to_origin = GetFragToOrigin(i);
 
-	float2 uv_channels = float2(_Custom30_Quaternion_UV_Channel_0, _Custom30_Quaternion_UV_Channel_1);
+  float2 uv_channels = float2(_Baked_Origins_UV_Channel_Index, _Baked_Origins_UV_Channel_Index+1);
   float4 quat = GetRotation(i, uv_channels);
   float4 iquat = float4(-quat.xyz, quat.w);
 
-  float3 ro = -frag_to_origin;
-  float3 rd = normalize(i.objPos - obj_space_camera_pos);
+  ro = -frag_to_origin;
+  rd = normalize(getObjPos(i) - obj_space_camera_pos);
   rd = rotate_vector(rd, iquat);
+}
+void GetObjPosNorm(v2f i, float3 lclPos, float3 lclNorm, float3 lclTang,
+    out float3 objPos, out float3 objNorm, out float3 objTan) {
+  float3 frag_to_origin = GetFragToOrigin(i);
+  float2 uv_channels = float2(_Baked_Origins_UV_Channel_Index, _Baked_Origins_UV_Channel_Index+1);
+  float4 quat = GetRotation(i, uv_channels);
+  float4 iquat = float4(-quat.xyz, quat.w);
+
+  float3 objHit = rotate_vector(lclPos, quat);
+  float3 objCenterOffset = rotate_vector(frag_to_origin, quat);
+  objPos = objHit + (getObjPos(i) + objCenterOffset);
+
+  objNorm = rotate_vector(lclNorm, quat);
+  objTan = rotate_vector(lclTang, quat);
+}
+#else
+void GetRoRd(v2f i, out float3 ro, out float3 rd) {
+  ro = getObjPos(i);
+  float3 objCamPos = mul(unity_WorldToObject, float4(_WorldSpaceCameraPos, 1));
+  float3 obj_space_camera_pos = mul(unity_WorldToObject, float4(_WorldSpaceCameraPos, 1.0));
+  rd = normalize(getObjPos(i) - obj_space_camera_pos);
+}
+void GetObjPosNorm(v2f i, float3 lclPos, float3 lclNorm, float3 lclTang,
+    out float3 objPos, out float3 objNorm, out float3 objTan) {
+  objPos = lclPos;
+  objNorm = lclNorm;
+  objTan = lclTang;
+}
+#endif  // _RAY_MARCHING_BAKED_ORIGINS
+
+RayMarchResult ray_march(v2f i) {
+  float3 ro, rd;
+  GetRoRd(i, ro, rd);
+
+  const float kMinDist = 1e-3;
+  // TODO dial this in & parameterize
+  const float kMaxDist = 10;
+  // TODO parameterize
+  const uint kMaxIter = 10;
+  float d_acc = 0;
+  for (uint ii = 0; ii < kMaxIter; ++ii) {
+    float3 p = ro + rd * d_acc;
+    float d_cur = map(p);
+    d_acc += d_cur;
+    if (d_cur < kMinDist) {
+      break;
+    }
+    if (d_acc > kMaxDist) {
+      break;
+    }
+  }
+
+  // TODO clip / hit detection
+  float3 lclPos = ro + rd * d_acc;
+  float3 lclNorm;
+  float3 lclTang;
+  map_normal(lclPos, lclNorm, lclTang);
+
+  RayMarchResult res;
+  GetObjPosNorm(i, lclPos, lclNorm, lclTang,
+      res.objPos, res.objNorm, res.objTan);
 
-  ro -= rd * _Custom30_ro_Offset;
+  return res;
 }
 
 #endif  // __RAY_MARCHING_INC