Can you freely compose signed distance functions? Obviously people use them for + and - regularly. My intuition says you should be able to apply *, / and more as well.
and
sqrt( sdEquilateralTriangle(pos.xy, 10)**2 + sdCircle(pos.xz,10)**2 )
seems like there's scope for a nice little domain specific language to.
I think it would be interesting to have some composite operations that did probabilistic branching based upon a hashing RNG to conditionally combine shapes
something like
float thingy(pos,r) {
float more = infinity
float pseudoRandom = HashToUnit(pos)
if (pseudoRandom >0.5) {
float direction=randomAngleFromSeed(pseudoRandom+r)
more = thingy(pos+direction*r, r*0.75)
}
return min(circle(pos,r),more)
}
You can take the minimum of two SDFs, which more or less gives you an SDF for their union. The maximum is the intersection. A few years ago I wrote a DSL that writes the SDFs for you, for my university programming languages course. https://github.com/SebastianMestre/school/tree/master/univer...
f * g is a symmetric difference (all zeros remain zeros, the new internal points are those that are inside exactly one of f and g: (-, +) -> -, (+, -) -> -, (+, +) -> +, (-, -) -> +).
f * g + x for some small constant x makes the symdiff smoother, depending on the sign of x it makes the components either meld together or "repel" each other. If the original components are disjoint (or if it's 3D solids and the internal surfaces are irrelevant) and x < 0, it functions as a smooth union.
f / g has the same inside/zero/outside behavior as f * g, but is of course very pathological for all values of g close to zero. I don't think it has any good uses.
I come back every couple of months when I have a new project involving sdfs. And almost every time it's a bit of trial and error figuring out the parameters. It's workable, but a minor pet peeve that they're not described or named better.
I was just about to say the same thing. This is bad code/documentation. Single letter variable names is almost always wrong if it isn't i for an index or such (and even then, would typing 'idx' kill you?). And as parameters, so much worse. Don't make me guess how to call your function please.
I owe this guy so much. A living legend.
Can you freely compose signed distance functions? Obviously people use them for + and - regularly. My intuition says you should be able to apply *, / and more as well.
and sqrt( sdEquilateralTriangle(pos.xy, 10)**2 + sdCircle(pos.xz,10)**2 )
seems like there's scope for a nice little domain specific language to.
I think it would be interesting to have some composite operations that did probabilistic branching based upon a hashing RNG to conditionally combine shapes
something like
You can take the minimum of two SDFs, which more or less gives you an SDF for their union. The maximum is the intersection. A few years ago I wrote a DSL that writes the SDFs for you, for my university programming languages course. https://github.com/SebastianMestre/school/tree/master/univer...
f * g is a symmetric difference (all zeros remain zeros, the new internal points are those that are inside exactly one of f and g: (-, +) -> -, (+, -) -> -, (+, +) -> +, (-, -) -> +).
f * g + x for some small constant x makes the symdiff smoother, depending on the sign of x it makes the components either meld together or "repel" each other. If the original components are disjoint (or if it's 3D solids and the internal surfaces are irrelevant) and x < 0, it functions as a smooth union.
f / g has the same inside/zero/outside behavior as f * g, but is of course very pathological for all values of g close to zero. I don't think it has any good uses.
I come back every couple of months when I have a new project involving sdfs. And almost every time it's a bit of trial and error figuring out the parameters. It's workable, but a minor pet peeve that they're not described or named better.
It's a priceless resource nevertheless.
I was just about to say the same thing. This is bad code/documentation. Single letter variable names is almost always wrong if it isn't i for an index or such (and even then, would typing 'idx' kill you?). And as parameters, so much worse. Don't make me guess how to call your function please.