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Content/Editor/MaterialTemplates/GPUParticles.shader

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+// File generated by Flax Editor
+// Version: @0
+
+@3
+#include "./Flax/Common.hlsl"
+#include "./Flax/GBufferCommon.hlsl"
+#include "./Flax/Matrix.hlsl"
+@7
+// Primary constant buffer
+META_CB_BEGIN(0, Data)
+float4x4 ViewProjectionMatrix;
+float4x4 InvViewProjectionMatrix;
+float4x4 InvViewMatrix;
+float4x4 ViewMatrix;
+float4x4 WorldMatrix;
+float4x4 InvWorldMatrix;
+float3 ViewPos;
+float ViewFar;
+float3 ViewDir;
+float Time;
+float4 ViewInfo;
+float4 ScreenSize;
+float3 EffectPosition;
+float DeltaTime;
+float4 EffectRotation;
+float3 EffectScale;
+uint ParticleCounterOffset;
+float3 Dummy0;
+uint SpawnCount;
+@1META_CB_END
+
+// Particles data buffers
+ByteAddressBuffer SrcParticlesData : register(t0);
+RWByteAddressBuffer DstParticlesData : register(u0);
+
+// The GPU particles simulation context data
+struct Context
+{
+	uint ParticleIndex;
+	uint ParticlesCount;
+	uint Seed;
+};
+
+@6
+// Seed generation function
+uint WangHash(uint seed)
+{
+	seed = (seed ^ 61) ^ (seed >> 16);
+	seed += (seed << 3);
+	seed = seed ^ (seed >> 4);
+	seed *= 0x27d4eb2d;
+	seed = seed ^ (seed >> 15);
+	return seed;
+}
+
+// Random number generation function
+float Rand(inout uint seed)
+{
+	const uint multiplier = 0x0019660d;
+	const uint increment = 0x3c6ef35f;
+	seed = multiplier * seed + increment;
+	return asfloat((seed >> 9) | 0x3f800000) - 1.0f;
+}
+
+float4 Mod289(float4 x)
+{
+	return x - floor(x * (1.0 / 289.0)) * 289.0;
+}
+
+float4 Perm(float4 x)
+{
+	return Mod289(((x * 34.0) + 1.0) * x);
+}
+
+float Noise(float3 p)
+{
+    float3 a = floor(p);
+    float3 d = p - a;
+    d = d * d * (3.0 - 2.0 * d);
+	
+    float4 b = a.xxyy + float4(0.0, 1.0, 0.0, 1.0);
+    float4 k1 = Perm(b.xyxy);
+    float4 k2 = Perm(k1.xyxy + b.zzww);
+	
+    float4 c = k2 + a.zzzz;
+    float4 k3 = Perm(c);
+    float4 k4 = Perm(c + 1.0);
+	
+    float4 o1 = frac(k3 * (1.0 / 41.0));
+    float4 o2 = frac(k4 * (1.0 / 41.0));
+	
+    float4 o3 = o2 * d.z + o1 * (1.0 - d.z);
+    float2 o4 = o3.yw * d.x + o3.xz * (1.0 - d.x);
+	
+    return o4.y * d.y + o4.x * (1.0 - d.y);
+}
+
+float3 Noise3D(float3 p)
+{
+    float o = Noise(p);
+    float a = Noise(p + float3(0.0001f, 0.0f, 0.0f));
+    float b = Noise(p + float3(0.0f, 0.0001f, 0.0f));
+    float c = Noise(p + float3(0.0f, 0.0f, 0.0001f));
+
+    float3 grad = float3(o - a, o - b, o - c);
+    float3 other = abs(grad.zxy);
+    return normalize(cross(grad,other));
+}
+
+float3 Noise3D(float3 position, int octaves, float roughness)
+{
+	float weight = 0.0f;
+	float3 noise = float3(0.0, 0.0, 0.0);
+	float scale = 1.0f;
+	for (int i = 0; i < octaves; i++)
+	{
+		float curWeight = pow((1.0-((float)i / octaves)), lerp(2.0, 0.2, roughness));
+		
+		noise += Noise3D(position * scale) * curWeight;
+		weight += curWeight;
+		
+		scale *= 1.72531;
+	}
+	return noise / weight;
+}
+
+// Reprojects the world space position from the given UV and raw device depth
+float3 ReprojectPosition(float2 uv, float rawDepth)
+{
+	uv = uv * float2(2.0, -2.0) + float2(-1.0, 1.0);
+	float4 pos = mul(float4(uv.x, uv.y, rawDepth, 1.0f), InvViewProjectionMatrix);
+	return pos.xyz / pos.w;
+}
+
+// Random values generation wrapper macros
+#define RAND Rand(context.Seed)
+#define RAND2 float2(RAND, RAND)
+#define RAND3 float3(RAND, RAND, RAND)
+#define RAND4 float4(RAND, RAND, RAND, RAND)
+
+@2uint GetParticleUint(uint particleIndex, int offset)
+{
+	return SrcParticlesData.Load(particleIndex * PARTICLE_STRIDE + offset);
+}
+
+int GetParticleInt(uint particleIndex, int offset)
+{
+	return asint(SrcParticlesData.Load(particleIndex * PARTICLE_STRIDE + offset));
+}
+
+float GetParticleFloat(uint particleIndex, int offset)
+{
+	return asfloat(SrcParticlesData.Load(particleIndex * PARTICLE_STRIDE + offset));
+}
+
+float2 GetParticleVec2(uint particleIndex, int offset)
+{
+	return asfloat(SrcParticlesData.Load2(particleIndex * PARTICLE_STRIDE + offset));
+}
+
+float3 GetParticleVec3(uint particleIndex, int offset)
+{
+	return asfloat(SrcParticlesData.Load3(particleIndex * PARTICLE_STRIDE + offset));
+}
+
+float4 GetParticleVec4(uint particleIndex, int offset)
+{
+	return asfloat(SrcParticlesData.Load4(particleIndex * PARTICLE_STRIDE + offset));
+}
+
+void SetParticleUint(uint particleIndex, int offset, uint value)
+{
+	DstParticlesData.Store(particleIndex * PARTICLE_STRIDE + offset, value);
+}
+
+void SetParticleInt(uint particleIndex, int offset, int value)
+{
+	DstParticlesData.Store(particleIndex * PARTICLE_STRIDE + offset, asuint(value));
+}
+
+void SetParticleFloat(uint particleIndex, int offset, float value)
+{
+	DstParticlesData.Store(particleIndex * PARTICLE_STRIDE + offset, asuint(value));
+}
+
+void SetParticleVec2(uint particleIndex, int offset, float2 value)
+{
+	DstParticlesData.Store2(particleIndex * PARTICLE_STRIDE + offset, asuint(value));
+}
+
+void SetParticleVec3(uint particleIndex, int offset, float3 value)
+{
+	DstParticlesData.Store3(particleIndex * PARTICLE_STRIDE + offset, asuint(value));
+}
+
+void SetParticleVec4(uint particleIndex, int offset, float4 value)
+{
+	DstParticlesData.Store4(particleIndex * PARTICLE_STRIDE + offset, asuint(value));
+}
+
+bool AddParticle(out uint dstIndex)
+{
+	// Acquire the particle index in the destination buffer
+	DstParticlesData.InterlockedAdd(ParticleCounterOffset, 1, dstIndex);
+	
+	// Prevent overflow
+	return dstIndex >= PARTICLE_CAPACITY;
+}
+
+void UpdateParticle(Context context)
+{
+@5}
+
+void SpawnParticle(Context context)
+{
+	if (AddParticle(context.ParticleIndex))
+		return;
+	
+@4}
+
+// Main entry point for the particles simulation and spawning
+META_CS(true, FEATURE_LEVEL_SM5)
+[numthreads(THREAD_GROUP_SIZE, 1, 1)]
+void CS_Main(uint3 dispatchThreadId : SV_DispatchThreadID)
+{
+	Context context;
+	context.ParticleIndex = dispatchThreadId.x;
+	context.ParticlesCount = min(SrcParticlesData.Load(ParticleCounterOffset), PARTICLE_CAPACITY);
+	context.Seed = WangHash(context.ParticleIndex ^ asuint(Time));
+	
+	if (context.ParticleIndex < context.ParticlesCount)
+	{
+		UpdateParticle(context);
+	}
+	else if (context.ParticleIndex < context.ParticlesCount + SpawnCount)
+	{
+		SpawnParticle(context);
+	}
+}