Line data    Source code

       1              : // simulate.slang — particle physics compute kernel entry point.
       2              : //
       3              : // The per-type physics helpers (`applyGravity`, `stepFluid`,
       4              : // `stepGas`, `stepSolid`) and the `Particle` struct live in
       5              : // `physics.slang` as a separate module. When `-trace-coverage` is
       6              : // on, counters are attributed to whichever file each statement
       7              : // came from, so the resulting LCOV report spans BOTH files — one
       8              : // `SF:` record per file, each with its own per-line hit counts.
       9              : 
      10              : import physics;
      11              : 
      12              : // Particle type discriminants. Matches the `PARTICLE_TYPE_*` enum
      13              : // on the host side.
      14              : static const uint PARTICLE_TYPE_FLUID = 0;
      15              : static const uint PARTICLE_TYPE_GAS   = 1;
      16              : static const uint PARTICLE_TYPE_SOLID = 2;
      17              : 
      18              : //TEST_INPUT: set particles = out ubuffer(data=[], stride=32)
      19              : RWStructuredBuffer<Particle> particles;
      20              : 
      21              : //TEST_INPUT: set params = ubuffer(data=[0], stride=4)
      22              : cbuffer Params
      23              : {
      24              :     uint  particleCount;
      25              :     float dt;
      26              : }
      27              : 
      28              : [numthreads(64, 1, 1)]
      29              : void computeMain(uint3 tid : SV_DispatchThreadID)
      30              : {
      31         1536 :     uint i = tid.x;
      32          512 :     if (i >= particleCount)
      33            0 :         return;
      34              : 
      35          512 :     Particle p = particles[i];
      36              : 
      37          512 :     if (p.type == PARTICLE_TYPE_FLUID)
      38              :     {
      39          352 :         stepFluid(p, dt);
      40              :     }
      41          336 :     else if (p.type == PARTICLE_TYPE_GAS)
      42              :     {
      43          336 :         stepGas(p, dt);
      44              :     }
      45          168 :     else if (p.type == PARTICLE_TYPE_SOLID)
      46              :     {
      47          336 :         stepSolid(p, dt);
      48              :     }
      49              :     else
      50              :     {
      51              :         // Unknown type — flag for host-side triage. This branch is
      52              :         // intentionally unreachable in the "normal" test scenarios;
      53              :         // the coverage report will show it uncovered, demonstrating
      54              :         // that the instrumentation spots dead code.
      55            0 :         p.flags |= 0x1u;
      56              :     }
      57              : 
      58          512 :     particles[i] = p;
      59              : }