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view demos/ray.d @ 1117:4c20fcc4252b
Fun with parameter attributes: For several of the "synthetic" parameters added
to D functions, we can apply noalias and nocapture. They are sret parameters,
'nest' pointers passed to nested functions, and _argptr:
Nocapture:
- Sret and nest are nocapture because they don't represent D-level variables,
and thus the callee can't (validly) obtain a pointer to them, let alone keep
it around after it returns.
- _argptr is nocapture because although the callee has access to it as a
pointer, that pointer is invalidated when it returns.
All three are noalias because they're function-local variables
- Sret and _argptr are noalias because they're freshly alloca'd memory only
used for a single function call that's not allowed to keep an aliasing
pointer to it around (since the parameter is nocapture).
- 'Nest' is noalias because the callee only ever has access to one such pointer
per parent function, and every parent function has a different one.
This commit also ensures attributes set on sret, _arguments and _argptr are
propagated to calls to such functions.
It also adds one exception to the general rule that attributes on function types
should propagate to calls: the type of a delegate's function pointer has a
'nest' parameter, but this can either be a true 'nest' (for delegates to nested
functions) or a 'this' (for delegates to member functions). Since 'this' is
neither noalias nor nocapture, and there's generally no way to tell which one it
is, we remove these attributes at the call site if the callee is a delegate.
author | Frits van Bommel <fvbommel wxs.nl> |
---|---|
date | Sat, 14 Mar 2009 22:15:31 +0100 |
parents | eef8ac26c66c |
children |
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line source
import tango.stdc.stdio; alias char[] string; int atoi(char[] s) { int i, fac=1; bool neg = (s.length) && (s[0] == '-'); char[] a = neg ? s[1..$] : s; foreach_reverse(c; a) { i += (c-'0') * fac; fac *= 10; } return !neg ? i : -i; } version(LDC) { pragma(intrinsic, "llvm.sqrt.f64") double sqrt(double val); } else { import tango.stdc.math; } double delta; static this() { delta=sqrt(real.epsilon); } struct Vec { double x, y, z; Vec opAdd(ref Vec other) { return Vec(x+other.x, y+other.y, z+other.z); } Vec opSub(ref Vec other) { return Vec(x-other.x, y-other.y, z-other.z); } Vec opMul(double a) { return Vec(x*a, y*a, z*a); } double dot(ref Vec other) { return x*other.x+y*other.y+z*other.z; } Vec unitise() { return opMul(1.0/sqrt(dot(*this))); } } struct Pair(T, U) { T first; U second; } typedef Pair!(double, Vec) Hit; struct Ray { Vec orig, dir; } class Scene { //abstract void intersect(ref Hit, ref Ray); void intersect(ref Hit, ref Ray) {} } class Sphere : Scene { Vec center; double radius; //mixin This!("center, radius"); this(ref Vec c, double r) { center = c; radius = r; } double ray_sphere(ref Ray ray) { auto v = center - ray.orig, b = v.dot(ray.dir), disc=b*b - v.dot(v) + radius*radius; if (disc < 0) return double.infinity; auto d = sqrt(disc), t2 = b + d; if (t2 < 0) return double.infinity; auto t1 = b - d; return (t1 > 0 ? t1 : t2); } void intersect(ref Hit hit, ref Ray ray) { auto lambda = ray_sphere(ray); if (lambda < hit.first) hit = Hit(lambda, (ray.orig + lambda*ray.dir - center).unitise); } } class Group : Scene { Sphere bound; Scene[] children; //mixin This!("bound, children"); this (Sphere s, Scene[] c) { bound = s; children = c; } void intersect(ref Hit hit, ref Ray ray) { auto l = bound.ray_sphere(ray); if (l < hit.first) foreach (child; children) child.intersect(hit, ray); } } double ray_trace(ref Vec light, ref Ray ray, Scene s) { auto hit=Hit(double.infinity, Vec(0, 0, 0)); s.intersect(hit, ray); if (hit.first == double.infinity) return 0.0; auto g = hit.second.dot(light); if (g >= 0) return 0.0; auto p = ray.orig + ray.dir*hit.first + hit.second*delta; auto hit2=Hit(double.infinity, Vec(0, 0, 0)); s.intersect(hit2, Ray(p, light*-1.0)); return (hit2.first < double.infinity ? 0 : -g); } Scene create(int level, ref Vec c, double r) { auto s = new Sphere(c, r); if (level == 1) return s; Scene[] children; children ~= s; double rn = 3*r/sqrt(12.0); for (int dz=-1; dz<=1; dz+=2) for (int dx=-1; dx<=1; dx+=2) children~=create(level-1, c + Vec(dx, 1, dz)*rn, r/2); return new Group(new Sphere(c, 3*r), children); } void main(string[] args) { int level = (args.length==3 ? args[1].atoi() : 9), n = (args.length==3 ? args[2].atoi() : 512), ss = 4; auto light = Vec(-1, -3, 2).unitise(); auto s=create(level, Vec(0, -1, 0), 1); printf("P5\n%d %d\n255\n", n,n); for (int y=n-1; y>=0; --y) for (int x=0; x<n; ++x) { double g=0; for (int d=0; d<ss*ss; ++d) { auto dir=Vec(x+(d%ss)*1.0/ss-n/2.0, y+(d/ss)*1.0/ss-n/2.0, n).unitise(); g += ray_trace(light, Ray(Vec(0, 0, -4), dir), s); } printf("%c", cast(ubyte)(0.5 + 255.0 * g / (ss*ss))); } }