Line data    Source code

       1              : // physics.slang — per-particle-type physics steps, split into its own
       2              : // module to demonstrate that `-trace-coverage` attributes counters
       3              : // correctly across multiple source files. The LCOV report produced
       4              : // by the demo will contain separate `SF:` records for this file and
       5              : // `simulate.slang`, each with its own per-line hit counts.
       6              : 
       7              : public struct Particle
       8              : {
       9              :     public float3 position;
      10              :     public float3 velocity;
      11              :     public uint   type;
      12              :     public uint   flags;
      13              : };
      14              : 
      15              : public float3 applyGravity(float3 velocity, float dt)
      16              : {
      17          688 :     return velocity + float3(0.0, -9.8, 0.0) * dt;
      18              : }
      19              : 
      20              : public void stepFluid(inout Particle p, float dt)
      21              : {
      22          528 :     p.velocity = applyGravity(p.velocity, dt);
      23              :     // Viscous drag proportional to speed.
      24          176 :     float speed = length(p.velocity);
      25          176 :     if (speed > 0.01)
      26          176 :         p.velocity -= normalize(p.velocity) * 0.5 * dt;
      27          176 :     p.position += p.velocity * dt;
      28              : }
      29              : 
      30              : public void stepGas(inout Particle p, float dt)
      31              : {
      32              :     // Gas rises buoyantly; no gravity pull, only ambient drag.
      33          504 :     p.velocity += float3(0.0, 2.5, 0.0) * dt;
      34          168 :     p.velocity *= 0.98;
      35          168 :     p.position += p.velocity * dt;
      36              : }
      37              : 
      38              : public void stepSolid(inout Particle p, float dt)
      39              : {
      40              :     // Solids fall under gravity; bounce on the floor.
      41          504 :     p.velocity = applyGravity(p.velocity, dt);
      42          168 :     p.position += p.velocity * dt;
      43          168 :     if (p.position.y < 0.0)
      44              :     {
      45            0 :         p.position.y = 0.0;
      46            0 :         p.velocity.y = -p.velocity.y * 0.6;  // inelastic bounce
      47              :     }
      48              : }