Differences

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--- particles [2020/11/06 13:51] – [Physics Particle Support] admin
+++ particles [2020/11/06 14:04] – admin
@@ Line 48: / Line 48: @@
 | a_Binormal | X = size, Y = angle, Z = weight |
 | a_Tangent | X = age, Y = life time, Z = delta time |
+===== Influencers =====
+Influencers are helper classes to manipulate particles at runtime.
 ===== Physics Particle Support =====
 {{::particles3.jpg?nolink|}}
+Our particles system can be linked to the physics system for particle collision detection.
+In the following example we use the rain particle emitter as basis.
+<file pascal>
+uses
+  [...]
+  Gorilla.Material.Particle,
+  Gorilla.Particle.Emitter,
+  Gorilla.Particle.Influencer,
+  Gorilla.Particle.Rain,
+  Gorilla.Particle.Spot,
+  Gorilla.Physics,
+  Gorilla.Physics.Q3.Body;
+TForm1 = class(TForm)
+  procedure FormCreate(Sender: TObject);
+  protected
+    FViewport : TGorillaViewport;
+    FCamera : TGorillaCamera;
+    FPhysics : TGorillaPhysicsSystem;
+    FParticles : TGorillaRainParticleEmitter;
+    FInfluencer : TGorillaPhysicsInfluencer;
+    FSplashes : TGorillaSpotParticleEmitter;
+    procedure DoOnGorillaPhysicsNotifyContact(const ABodyA, ABodyB : TQ3Body);
+  [...]
+end;
+[...]
+procedure TForm1.DoOnGorillaPhysicsNotifyContact(const ABodyA, ABodyB : TQ3Body);
+begin
+  // collision detected - create splashes on particle-sphere/box/terrain/mesh collision
+  // not on particle-particle collision (too much)
+  if (PTypeInfo(ABodyA.UserDataType) = TypeInfo(PGorillaParticle))
+  and (PTypeInfo(ABodyB.UserDataType) = TypeInfo(PGorillaParticle)) then
+    Exit;
+  if (PTypeInfo(ABodyA.UserDataType) = TypeInfo(PGorillaParticle)) then
+    FSplashes.EmitParticle(
+      PGorillaParticle(ABodyA.UserData)^.Position
+      )
+  else if (PTypeInfo(ABodyB.UserDataType) = TypeInfo(PGorillaParticle)) then
+    FSplashes.EmitParticle(
+      PGorillaParticle(ABodyB.UserData)^.Position
+      );
+end;
+procedure TForm1.FormCreate(Sender: TObject);
+begin
+  [...]
+  // create physics system with contact callback function to display splashes
+  FPhysics := TGorillaPhysicsSystem.Create(FViewport);
+  FPhysics.OnBeginContact := DoOnGorillaPhysicsNotifyContact;
+  // create rain particle emitter
+  FParticles := TGorillaRainParticleEmitter.Create(FViewport);
+  FParticles.Parent := FViewport;
+  FParticles.Camera := FCamera;
+  FParticles.EmitParticles := 25;
+  // preconfigure particles
+  FParticles.Colored.StartColor := TAlphaColorF.Create( TAlphaColorRec.Blue );
+  FParticles.Colored.EndColor := TAlphaColorF.Create( TAlphaColorRec.Blueviolet );
+  FParticles.ParticleSize   := TParticlePreset.Create(20, 20, 1, false);
+  FParticles.ParticleGrowth := TParticlePreset.Create(0, 0, 1, false);
+  FParticles.Colored.Enabled := false;
+  FParticles.Wind.Enabled := false;
+  // create a physics influencer
+  FInfluencer := TGorillaPhysicsInfluencer.Create(FParticles);
+  FInfluencer.Emitter := FParticles;
+  // link to physics system component
+  FInfluencer.Physics := FPhysics;
+  FInfluencer.Enabled := true;
+  // another particle emitter to simulate rain drop splashes when they hit an obstacle
+  FSplashes := TGorillaSpotParticleEmitter.Create(FViewport);
+  FSplashes.Parent := FViewport;
+  FSplashes.Camera := FCamera;
+  FSplashes.LoadTexture('splash.png');
+  // activate physics
+  FPhysics.Active := true;
+  FParticles.Start();
+  FSplashes.Start();
+end;
+</file>
 ===== Example =====