ref: 590c394f3cf8e8f6c8612ff8feb76a2c78a59613
parent: 9a4039805fa1d7a99929e7254a6bde3fb8e1dc2e
author: rodri <rgl@antares-labs.eu>
date: Thu Jul 24 12:25:42 EDT 2025
new tool: raymarch
--- a/mkfile
+++ b/mkfile
@@ -12,6 +12,7 @@
stl\
tostl\
plot3\
+ raymarch\
OFILES=\
alloc.$O\
--- /dev/null
+++ b/raymarch.c
@@ -1,0 +1,321 @@
+/*
+ * based on kishimisu's “An Introduction to Raymarching”
+ * - https://www.youtube.com/watch?v=khblXafu7iA
+ */
+#include <u.h>
+#include <libc.h>
+#include <thread.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <mouse.h>
+#include <keyboard.h>
+#include <geometry.h>
+#include "libgraphics/graphics.h"
+#include "fns.h"
+
+#define sd∪(a, b) min((a), (b))
+#define sd∩(a, b) max((a), (b))
+#define sdsub(a, b) max(-(a), (b))
+
+Mousectl *mctl;
+Keyboardctl *kctl;
+Channel *drawc;
+Image *screenb;
+Camera *cam;
+Scene *scn;
+Entity *ent;
+Model *mdl;
+
+static int doprof;
+
+static Point3
+abspt3(Point3 p)
+{+ return (Point3){+ fabs(p.x),
+ fabs(p.y),
+ fabs(p.z),
+ fabs(p.w)
+ };
+}
+
+static double
+smin(double a, double b, double k)
+{+ double h;
+
+ h = max(k - fabs(a - b), 0)/k;
+ return min(a, b) - h*h*h * k/6;
+}
+
+static double
+sdBox(Point3 p, Point3 span)
+{+ double tmp;
+
+ p = subpt3(abspt3(p), span);
+ tmp = min(max(p.x, max(p.y, p.z)), 0);
+ return vec3len(maxpt3(p, ZP3)) + tmp;
+}
+
+static double
+sdSphere(Point3 p, double r)
+{+ return vec3len(p) - r;
+}
+
+static double
+map(Point3 p, double dt)
+{+ enum {+ RADIUS = 1,
+ SIDELEN = 0.75,
+ };
+ Point3 sphp;
+ double sphere, box, gnd;
+
+ sphp = Pt3(sin(dt)*3, 0, 0, 1);
+ sphere = sdSphere(subpt3(p, sphp), RADIUS);
+ box = sdBox(p, Vec3(SIDELEN, SIDELEN, SIDELEN));
+ gnd = p.y + 0.75;
+
+ return sd∪(gnd, smin(sphere, box, 2));
+}
+
+static Point3
+vs(Shaderparams *sp)
+{+ return sp->v->p;
+}
+
+static Color
+fs(Shaderparams *sp)
+{+ Vertexattr *va;
+ Point2 uv, m;
+ Point3 mpt, ro, rd, p;
+ Color c;
+ double time, dt, t, d;
+ int i;
+
+ uv = Pt2(sp->p.x, sp->p.y, 1);
+ uv.x = 2*uv.x - Dx(sp->su->fb->r);
+ uv.y = Dy(sp->su->fb->r) - 2*uv.y;
+ uv = divpt2(uv, Dy(sp->su->fb->r));
+
+ va = sp->getuniform(sp, "time");
+ time = va == nil? 0: va->n;
+ dt = time/1e9;
+
+ va = sp->getuniform(sp, "mouse");
+ mpt = va == nil? ZP3: va->p;
+ m = Pt2(mpt.x, mpt.y, 1);
+ m.x = 2*m.x - Dx(sp->su->fb->r);
+ m.y = Dy(sp->su->fb->r) - 2*m.y;
+ m = divpt2(m, Dy(sp->su->fb->r)/2);
+
+ ro = Pt3(0, 0, 3, 1);
+ rd = normvec3(Vec3(uv.x, uv.y, -1));
+ t = 0;
+
+ ro = qrotate(qrotate(ro, Vec3(0,1,0), -m.x), Vec3(1,0,0), m.y);
+ rd = qrotate(qrotate(rd, Vec3(0,1,0), -m.x), Vec3(1,0,0), m.y);
+
+ for(i = 0; i < 20; i++){+ p = addpt3(ro, mulpt3(rd, t));
+ d = map(p, dt);
+ t += d;
+
+ if(d < 0.001 || t > 100)
+ break;
+ }
+
+ c = mulpt3(Vec3(t, t, t), 0.2);
+ c.a = 1;
+ return srgb2linear(c);
+}
+
+Shadertab shaders = {+ .vs = vs,
+ .fs = fs
+};
+
+void
+redraw(void)
+{+ lockdisplay(display);
+ draw(screen, screen->r, screenb, nil, ZP);
+ flushimage(display, 1);
+ unlockdisplay(display);
+}
+
+void
+drawproc(void *)
+{+ threadsetname("drawproc");+
+ for(;;){+ recv(drawc, nil);
+ redraw();
+ }
+}
+
+void
+renderproc(void *)
+{+ Point3 mpt;
+ uvlong t0, Δt;
+ double time;
+
+ threadsetname("renderproc");+
+ t0 = nanosec();
+ for(;;){+ time = nanosec();
+ setuniform(&shaders, "time", VANumber, &time);
+ mpt = Vec3(mctl->xy.x, mctl->xy.y, 0);
+ setuniform(&shaders, "mouse", VAPoint, &mpt);
+ shootcamera(cam, &shaders);
+
+ Δt = nanosec() - t0;
+ if(Δt > HZ2NS(60)){+ lockdisplay(display);
+ draw(screenb, screenb->r, display->black, nil, ZP);
+ cam->view->draw(cam->view, screenb, nil);
+ unlockdisplay(display);
+ nbsend(drawc, nil);
+ t0 = nanosec();
+ }else{+ Δt = HZ2NS(60) - Δt;
+ if(Δt > 1000000ULL)
+ sleep(Δt/1000000ULL);
+ else
+ sleep(1);
+ }
+ }
+}
+
+void
+mouse(void)
+{+ mctl->xy = subpt(mctl->xy, screen->r.min);
+}
+
+void
+resize(void)
+{+ lockdisplay(display);
+ if(getwindow(display, Refnone) < 0)
+ fprint(2, "can't reattach to window\n");
+ unlockdisplay(display);
+ nbsend(drawc, nil);
+}
+
+void
+key(Rune r)
+{+ switch(r){+ case Kdel:
+ case 'q':
+ threadexitsall(nil);
+ }
+}
+
+static void
+confproc(void)
+{+ char buf[64];
+ int fd;
+
+ snprint(buf, sizeof buf, "/proc/%d/ctl", getpid());
+ fd = open(buf, OWRITE);
+ if(fd < 0)
+ sysfatal("open: %r");+
+ if(doprof)
+ fprint(fd, "profile\n");
+ close(fd);
+}
+
+void
+usage(void)
+{+ fprint(2, "usage: %s\n", argv0);
+ exits("usage");+}
+
+void
+threadmain(int argc, char *argv[])
+{+ Renderer *rctl;
+ Primitive quad[2];
+ Vertex v;
+ Rune r;
+
+ ARGBEGIN{+ case 'p': doprof++; break;
+ default: usage();
+ }ARGEND;
+ if(argc != 0)
+ usage();
+
+ confproc();
+
+ if(memimageinit() != 0)
+ sysfatal("memimageinit: %r");+ if((rctl = initgraphics()) == nil)
+ sysfatal("initgraphics: %r");+ if(initdraw(nil, nil, "raymarch") < 0)
+ sysfatal("initdraw: %r");+ if((mctl = initmouse(nil, screen)) == nil)
+ sysfatal("initmouse: %r");+ if((kctl = initkeyboard(nil)) == nil)
+ sysfatal("initkeyboard: %r");+
+ rctl->doprof = doprof;
+
+ scn = newscene(nil);
+ mdl = newmodel();
+ ent = newentity(nil, mdl);
+
+ screenb = eallocimage(display, rectsubpt(screen->r, screen->r.min), XRGB32, 0, DNofill);
+ cam = Cam(screenb->r, rctl, ORTHOGRAPHIC, 40*DEG, 1, 10);
+ placecamera(cam, scn, Pt3(0,0,0,1), Vec3(0,0,-1), Vec3(0,1,0));
+
+ quad[0] = quad[1] = mkprim(PTriangle);
+ v = mkvert();
+ v.p = mdl->addposition(mdl, vcs2clip(cam, viewport2vcs(cam, Pt3(screenb->r.min.x, screenb->r.max.y, 1, 1))));
+ quad[0].v[0] = mdl->addvert(mdl, v);
+ v.p = mdl->addposition(mdl, vcs2clip(cam, viewport2vcs(cam, Pt3(screenb->r.max.x, screenb->r.min.y, 1, 1))));
+ quad[0].v[1] = mdl->addvert(mdl, v);
+ v.p = mdl->addposition(mdl, vcs2clip(cam, viewport2vcs(cam, Pt3(screenb->r.min.x, screenb->r.min.y, 1, 1))));
+ quad[0].v[2] = mdl->addvert(mdl, v);
+ quad[1].v[0] = quad[0].v[0];
+ v.p = mdl->addposition(mdl, vcs2clip(cam, viewport2vcs(cam, Pt3(screenb->r.max.x, screenb->r.max.y, 1, 1))));
+ quad[1].v[1] = mdl->addvert(mdl, v);
+ quad[1].v[2] = quad[0].v[1];
+ mdl->addprim(mdl, quad[0]);
+ mdl->addprim(mdl, quad[1]);
+ scn->addent(scn, ent);
+
+ drawc = chancreate(sizeof(void*), 1);
+ display->locking = 1;
+ unlockdisplay(display);
+
+ proccreate(renderproc, nil, mainstacksize);
+ proccreate(drawproc, nil, mainstacksize);
+
+ enum {MOUSE, RESIZE, KEY};+ Alt a[] = {+ {mctl->c, &mctl->Mouse, CHANRCV},+ {mctl->resizec, nil, CHANRCV},+ {kctl->c, &r, CHANRCV},+ {nil, nil, CHANEND}+ };
+ for(;;)
+ switch(alt(a)){+ case MOUSE: mouse(); break;
+ case RESIZE: resize(); break;
+ case KEY: key(r); break;
+ }
+}
--
⑨