Add shatter wave gimmick

1 files changed, 20 insertions, 0 deletions

diff --git a/math.cginc b/math.cginc
index f44aa74..78b93ec 100644
--- a/math.cginc
+++ b/math.cginc
@@ -207,4 +207,24 @@ float median(float3 x) {
   return (x.r + x.g + x.b) - (x_min + x_max);

 }

 

+// Quaternions

+float4 qmul(float4 q1, float4 q2)

+{

+  return float4(

+      q2.xyz * q1.w + q1.xyz * q2.w + cross(q1.xyz, q2.xyz),

+      q1.w * q2.w - dot(q1.xyz, q2.xyz));

+}

+

+// Vector rotation with a quaternion

+// http://mathworld.wolfram.com/Quaternion.html

+float3 rotate_vector(float3 v, float4 r)

+{

+  float4 r_c = r * float4(-1, -1, -1, 1);

+  return qmul(r, qmul(float4(v, 0), r_c)).xyz;

+}

+

+float4 get_quaternion(float3 axis_normal, float theta) {

+  return float4(axis_normal * sin(theta / 2), cos(theta / 2));

+}

+

 #endif  // __MATH_INC