tessellate in screen space, and add sine wave deformation effect

1 files changed, 29 insertions, 17 deletions

diff --git a/vertex_deformation.slang b/vertex_deformation.slang
index 63ce1a4..f4d4132 100644
--- a/vertex_deformation.slang
+++ b/vertex_deformation.slang
@@ -3,15 +3,18 @@
 
 #define PI     3.14159265f
 #define PI_RCP 0.31830988f
+#define TAU    (2.0f * PI)
+
+#define glsl_mod(x,y) (((x)-(y)*floor((x)/(y))))
 
 // Differentiable versions of common operators.
-#define dabs(x) length(float2(x, 1e-6))
+#define dabs(x) sqrt((x) * (x) + 1e-6)
 #define dlerp(x, y, t) ((x) * (1-t) + (y) * t)
 
 // Macros for transforming normal and tangent using autodiff.
 // r3r3 refers to "r3 to r3 transform", aka a mapping between 3d real-valued
 // spaces.
-#define R3R3_DECLARE_BASIS_VECTORS \
+#define R3R3_DECLARE_BASIS_VECTORS(xyz) \
   DifferentialPair<float3> dp_x = diffPair(xyz, float3(1, 0, 0)); \
   DifferentialPair<float3> dp_y = diffPair(xyz, float3(0, 1, 0)); \
   DifferentialPair<float3> dp_z = diffPair(xyz, float3(0, 0, 1))
@@ -33,18 +36,13 @@
   tangent = mul(jacobian, tangent)
 
 // Syntactic sugar - wraps the previous three macros.
-#define R3R3_NORMALS(normal, tangent, fun, ...) \
-  R3R3_DECLARE_BASIS_VECTORS;   \
-  R3R3_AUTODIFF_BASIS_VECTORS(fun, __VA_ARGS__);  \
+#define R3R3_NORMALS(xyz, normal, tangent, fun, ...)  \
+  R3R3_DECLARE_BASIS_VECTORS(xyz);                    \
+  R3R3_AUTODIFF_BASIS_VECTORS(fun, __VA_ARGS__);      \
   R3R3_DEFORM_NORMAL_AND_TANGENT(normal, tangent)
 
 float3x3 inverse(float3x3 m, float det) {
-  if (abs(det) < 1e-9) {
-    return float3x3(
-        1,0,0,
-        0,1,0,
-        0,0,1);
-  }
+  det = max(1e-6 * abs(det), abs(det)) * sign(det);
 
   float invDet = 1.0f / det;
   float3x3 inv;
@@ -71,7 +69,7 @@ public float3 plane_to_tube(float3 xyz, no_diff float t) {
   float z0 = xyz.z;
 
   float theta = x0 * PI;
-  float radius = ((1.0f - z0) / (t * t + 1e-3)) * sign(t);
+  float radius = ((1.0f - z0) / (dabs(t) + 1e-4f)) * sign(t);
 
   float x = sin(theta / radius) * radius * PI_RCP;
   // The z0 term here is required to make the jacobian invertible.
@@ -82,7 +80,7 @@ public float3 plane_to_tube(float3 xyz, no_diff float t) {
 
 public void plane_to_tube_normal(float3 xyz, inout float3 normal,
     inout float3 tangent, float t) {
-  R3R3_NORMALS(normal, tangent, plane_to_tube, t);
+  R3R3_NORMALS(xyz, normal, tangent, plane_to_tube, t);
 }
 
 [Differentiable]
@@ -93,7 +91,7 @@ public float3 seal(float3 xyz, no_diff float A, no_diff float k, no_diff float t
 
   float x0 = x + sin(y * k) * 0.1;
   float y0 = y + sin(x * k * 2) * 0.5 + cos(z);
-  float z0 = (z + sin(x * y * k * PI + t) * A) * (1.0 + sin(y * k) * sin(x * k));
+  float z0 = (z + sin(x * y * k * PI + t)) * A * (1.0 + sin(y * k) * sin(x * k));
 
   x0 += z0 * 0.1 * sin(z0 * PI + 1.5);
   y0 += z0 * 0.1 * sin(z0 * PI + 1.5);
@@ -106,11 +104,25 @@ public float3 seal(float3 xyz, no_diff float A, no_diff float k, no_diff float t
   );
 }
 
-// Deform a normal vector using the inverse transpose of the jacobian.
 public void seal_normal(float3 xyz, inout float3 normal,
     inout float3 tangent, float A, float k, float t) {
-  R3R3_NORMALS(normal, tangent, seal, A, k, t);
+  R3R3_NORMALS(xyz, normal, tangent, seal, A, k, t);
 }
 
-#endif  // __CUSTOM31_INC
+[Differentiable]
+public float3 sine_wave(float3 xyz,
+    no_diff float3 amplitude,
+    no_diff float3 direction,
+    no_diff float3 k,
+    no_diff float3 omega,
+    no_diff float t) {
+  xyz += amplitude * sin(k * dot(xyz, direction) + omega * t);
+  return xyz;
+}
 
+public void sine_wave_normal(float3 xyz, inout float3 normal, inout float3 tangent,
+    float3 amplitude, float3 direction, float3 k, float3 omega, float t) {
+  R3R3_NORMALS(xyz, normal, tangent, sine_wave, amplitude, direction, k, omega, t);
+}
+
+#endif  // __CUSTOM31_INC