您最多选择25个主题 主题必须以中文或者字母或数字开头,可以包含连字符 (-),并且长度不得超过35个字符
 
 
 
 

70 行
2.3 KiB

#ifndef UNITY_REFRACTION_INCLUDED
#define UNITY_REFRACTION_INCLUDED
//-----------------------------------------------------------------------------
// Util refraction
//-----------------------------------------------------------------------------
struct RefractionModelResult
{
float distance; // length of the transmission during refraction through the shape
float3 positionWS; // out ray position
float3 rayWS; // out ray direction
};
RefractionModelResult RefractionModelSphere(float3 V, float3 positionWS, float3 normalWS, float ior, float thickness)
{
// Sphere shape model:
// We approximate locally the shape of the object as sphere, that is tangent to the shape.
// The sphere has a diameter of {thickness}
// The center of the sphere is at {positionWS} - {normalWS} * {thickness}
//
// So the light is refracted twice: in and out of the tangent sphere
// First refraction (tangent sphere in)
// Refracted ray
float3 R1 = refract(-V, normalWS, 1.0 / ior);
// Center of the tangent sphere
float3 C = positionWS - normalWS * thickness * 0.5;
// Second refraction (tangent sphere out)
float NoR1 = dot(normalWS, R1);
// Optical depth within the sphere
float distance = -NoR1 * thickness;
// Out hit point in the tangent sphere
float3 P1 = positionWS + R1 * distance;
// Out normal
float3 N1 = normalize(C - P1);
// Out refracted ray
float3 R2 = refract(R1, N1, ior);
float N1oR2 = dot(N1, R2);
float VoR1 = dot(V, R1);
RefractionModelResult result;
result.distance = distance;
result.positionWS = P1;
result.rayWS = R2;
return result;
}
RefractionModelResult RefractionModelPlane(float3 V, float3 positionWS, float3 normalWS, float ior, float thickness)
{
// Plane shape model:
// We approximate locally the shape of the object as a plane with normal {normalWS} at {positionWS}
// with a thickness {thickness}
// Refracted ray
float3 R = refract(-V, normalWS, 1.0 / ior);
// Optical depth within the thin plane
float distance = thickness / dot(R, -normalWS);
RefractionModelResult result;
result.distance = distance;
result.positionWS = positionWS + R * distance;
result.rayWS = -V;
return result;
}
#endif