Raymarching A Donut Deformation

定义function

在hlsl中定义function

float3 color(float r, float g, float b)
{return float3(r, g, b);
}
return color(1.0f, 1.0f, 0.0f);

这样定义会报错，不允许单独的定义function

struct MyFunction
{float3 color(float r, float g, float b){return float3(r, g, b);}
};
MyFunction myFunction;
return myFunction.color(1.0f, 1.0f, 0.0f);

把function写到一个struct中定义就可以了

donut

制作一个甜甜圈，首先是定义甜甜圈的形状

float3 rayOrigin = worldPos - viewDir;
float3 offset = viewDir * -1;struct  MyFunction
{float donut(float3 p, float size, float cutout){float2 q = float2(length(p.xz) - size, p.y);return length(q) - cutout;}
}myFunction;for(int i = 0; i < 256; i++)
{float dist = myFunction.donut(rayOrigin, 50, 25);if (dist < 0.01f){mask = 1.0;float3 normal = float3(0.0f, 0.0f, 0.0f);float diffuse = max(dot(normal, lightPos), 0.0f);float3 h = normalize((viewDir + lightPos));float spec = pow(max(dot(normal, h), 0.0f), specRate);return float3(1.0f, 0.0f, 0.0f) * diffuse + float3(1.0f, 1.0f, 1.0f) * spec;}rayOrigin += offset;
}
mask = 0.0;
return float3(0.0f, 0.0f, 0.0f);

主要就是定义fcuntion的方式我们要知道。

定义normal

float3 rayOrigin = worldPos - viewDir;
float3 offset = viewDir * -1;struct MyFunction
{float donut(float3 p, float size, float cutout){float2 q = float2(length(p.xz) - size, p.y);return length(q) - cutout;}
}myFunction;float eps = 0.001;
for(int i = 0; i < 256; i++)
{float dist = myFunction.donut(rayOrigin, 50, 25);if (dist < 0.01f){mask = 1.0;float3 normal = normalize(float3(myFunction.donut(float3(rayOrigin.x + eps, rayOrigin.y, rayOrigin.z), 50, 25)- myFunction.donut(float3(rayOrigin.x - eps, rayOrigin.y, rayOrigin.z), 50, 25),myFunction.donut(float3(rayOrigin.x, rayOrigin.y + eps, rayOrigin.z), 50, 25)- myFunction.donut(float3(rayOrigin.x, rayOrigin.y - eps, rayOrigin.z), 50, 25),myFunction.donut(float3(rayOrigin.x, rayOrigin.y, rayOrigin.z + eps), 50, 25)- myFunction.donut(float3(rayOrigin.x, rayOrigin.y, rayOrigin.z - eps), 50, 25)));float diffuse = max(dot(normal, lightPos), 0.0f);float3 h = normalize((viewDir + lightPos));float spec = pow(max(dot(normal, h), 0.0f), specRate);return float3(1.0f, 0.0f, 0.0f) * diffuse + float3(1.0f, 1.0f, 1.0f) * spec;}rayOrigin += offset;
}
mask = 0.0;
return float3(0.0f, 0.0f, 0.0f);