diff options
Diffstat (limited to 'math.cginc')
| -rw-r--r-- | math.cginc | 42 |
1 files changed, 22 insertions, 20 deletions
@@ -3,13 +3,17 @@ #include "pema99.cginc"
-#define PI 3.14159265358979323846264
-#define TAU (2 * PI)
-#define HALF_PI (PI * 0.5)
+#define PI 3.14159265358979323846264f
+#define TAU (2.0f * PI)
+#define HALF_PI (PI * 0.5f)
+#define RCP_PI (1.0f / PI)
+#define RCP_TAU (1.0f / TAU)
#define PHI 1.618033989f
+#define RCP_PHI 0.618033989f
#define SQRT_2 1.414213562f
#define SQRT_2_RCP 0.707106781f
#define RCP_SQRT_2 0.707106781f
+#define RCP_SQRT_3 0.577350269f
#define TWO_OVER_THREE 0.6666666666666666f
#define SQRT_3_OVER_2 0.8660254037844386f
#define EULERS_CONSTANT 2.718281828f
@@ -21,24 +25,22 @@ float pow5(float x) return (tmp * tmp) * x;
}
+// Wrap NoL. Assume it's already clamped.
+// At k=0, you get standard lambertian shading.
+// At k=0.5, you get half-lambertian shading.
+// At k=1.0, you get flat shading.
+// k must be on [0, 1].
+// Energy preserving, within some small bound.
float wrapNoL(float NoL, float k) {
-#if 0
- // https://www.iro.umontreal.ca/~derek/files/jgt_wrap_final.pdf
- return pow(max(1E-4, (NoL + k) / (1 + k)), 1 + k);
-#else
- float k_sq = k * k;
- float b = max(0, lerp(NoL, 1.0, k));
- float p = -6.0 * k_sq + 5.0 * k + 1.0;
- // Using the formula
- float F = pow(b, p);
-
- // Approximate integral of NoL with respect to theta
- float I = (0.7856 * k_sq - 0.2148 * k) + 1.0;
-
- float G = F / max(I, 1E-6);
-
- return G;
-#endif
+ float lambertian = NoL;
+ float half_lambertian = pow(max(1e-4, (NoL + 0.5f) / (1.0f + 0.5f)), 2);
+ float flat = RCP_PI;
+
+ if (k < 0.5) {
+ return lerp(lambertian, half_lambertian, k * 2.0f);
+ } else {
+ return lerp(half_lambertian, flat, k * 2.0f - 1.0f);
+ }
}
float halfLambertianNoL(float NoL) {
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