add ex-verlet-pack example

examples/verlet/cpack.c

@@ -0,0 +1,76 @@
+#include "io/svg.h"
+#include "math/math.h"
+#include "math/vec.h"
+#include "sim/verlet.h"
+
+#define NUM 276
+
+static CT_SVGAttribs *doc_attribs;
+static CT_SVGAttribs *group_attribs;
+
+void outputFrame(CT_Verlet *phys, size_t frame) {
+  char fname[64];
+  snprintf(fname, 64, "assets/verlet-%04zu.svg", frame);
+  CT_INFO("---------- writing: %s", fname);
+  FILE *out = fopen(fname, "w");
+  ct_svg_start_doc(out, doc_attribs);
+  ct_svg_start_group(out, group_attribs);
+  for (size_t i = 0; i < phys->numP; i++) {
+    float p[3];
+    ct_verlet_pos2f(phys, i, p);
+    ct_svg_write_circle(out, p[0], p[1], p[2], NULL);
+  }
+  ct_svg_end_group(out);
+  ct_svg_end_doc(out);
+  fclose(out);
+}
+
+void spawn_particle(CT_Verlet *phys, CT_Vec2f *p, size_t id) {
+  CT_Vec2f q;
+  int ok;
+  float r =
+      ct_rand_normpos() < 1.1 ? ct_rand_minmax(4, 30) : ct_rand_minmax(2, 4);
+  float raccept = (r * 0.5) * (r * 0.5);
+  do {
+    q.x = ct_rand_normpos() * r * 2 + p->x;
+    q.y = ct_rand_normpos() * r * 2 + p->y;
+    ok  = (id == 0);
+    for (size_t i = 0, j = id << 1; i < j && !ok; i += 2) {
+      ok = (ct_distsq2fv(&q, (CT_Vec2f *)&phys->pos[i]) >= raccept);
+    }
+  } while (!ok);
+  ct_verlet_set2f(phys, id, (float *)&q, r);
+}
+
+int main() {
+  // clang-format off
+  CT_Verlet phys = {
+    .bounds    = {20, 20, 580, 580},
+    .gravity   = {0.0, 0.0},
+    .friction  = 0.5,
+    .repulsion = 1.0,
+    .maxForce  = 20,
+    .iter      = 4
+  };
+  // clang-format off
+  if (ct_verlet_init2d(&phys, NUM, 0, IVEC(120, 120, 120))) {
+    return 1;
+  }
+  ct_spgrid_trace(&phys.accel);
+  srand(time(0));
+  doc_attribs = ct_svg_attribs(0, 2, SVG_INT("width", 600), SVG_INT("height", 600));
+  group_attribs = ct_svg_attribs(0, 2, SVG_STR("fill", "none"), SVG_HEX("stroke", 0x0));
+  outputFrame(&phys, 0);
+  for (size_t i = 1; i < 100; i++) {
+    size_t num = CT_MIN(i * 64, NUM);
+    CT_Vec2f *p = (CT_Vec2f*)&phys.pos[num - 1];
+    for(size_t j = phys.numP; j< num; j++) {
+      spawn_particle(&phys, p, j);
+    }
+    phys.numP = num;
+    CT_TIMED(ct_verlet_update2d(&phys));
+    outputFrame(&phys, i);
+  }
+  ct_verlet_free(&phys);
+  return 0;
+}

premake5.lua

@@ -114,7 +114,15 @@ flags { "LinkTimeOptimization" }
 
 project "ex-verlet"
 kind "ConsoleApp"
-files { "examples/verlet/*.c" }
+files { "examples/verlet/main.c" }
+includedirs { "examples/common", "examples/verlet" }
+links "lib"
+dependson "lib"
+flags { "LinkTimeOptimization" }
+
+project "ex-verlet-pack"
+kind "ConsoleApp"
+files { "examples/verlet/cpack.c" }
 includedirs { "examples/common", "examples/verlet" }
 links "lib"
 dependson "lib"