Added a particle index output to the Particle Info Cycles node. This is required to get consistent ID numbers for particles. The Object ID is not usable since it's a user defined value of the instanced object, which does not vary per instance. Also the random value from the object info node is not consistent over time, since it only depends on the index in the dupli list (so each emitted or dying particle shifts the value).

The particle index is always the same for a specific particle. Randomized values can be generated from this with the use of a noise texture.

7 files changed, 31 insertions, 3 deletions

diff --git a/intern/cycles/blender/blender_particles.cpp b/intern/cycles/blender/blender_particles.cpp
index f591aaa6d83..d669aa34a68 100644
--- a/intern/cycles/blender/blender_particles.cpp
+++ b/intern/cycles/blender/blender_particles.cpp
@@ -144,16 +144,20 @@ void BlenderSync::sync_particles(Object *ob, BL::Object b_ob)
 	BL::Object::particle_systems_iterator b_psys;
 	for(b_ob.particle_systems.begin(b_psys); b_psys != b_ob.particle_systems.end(); ++b_psys) {
 		if (use_particle_system(*b_psys)) {
+			int pa_index = 0;
 			BL::ParticleSystem::particles_iterator b_pa;
 			for(b_psys->particles.begin(b_pa), index = 0; b_pa != b_psys->particles.end(); ++b_pa, ++index) {
 				if(use_particle(*b_pa)) {
 					Particle pa;
 					
+					pa.index = pa_index;
 					pa.age = b_scene.frame_current() - b_pa->birth_time();
 					pa.lifetime = b_pa->lifetime();
 					
 					ob->particles.push_back(pa);
 				}
+				
+				++pa_index;
 			}
 		}
 	}
diff --git a/intern/cycles/kernel/kernel_object.h b/intern/cycles/kernel/kernel_object.h
index 18e0b1e8a87..4ff315ca265 100644
--- a/intern/cycles/kernel/kernel_object.h
+++ b/intern/cycles/kernel/kernel_object.h
@@ -169,20 +169,27 @@ __device int shader_pass_id(KernelGlobals *kg, ShaderData *sd)
 	return kernel_tex_fetch(__shader_flag, (sd->shader & SHADER_MASK)*2 + 1);
 }
 
-__device float particle_age(KernelGlobals *kg, int particle)
+__device_inline float particle_index(KernelGlobals *kg, int particle)
 {
 	int offset = particle*PARTICLE_SIZE;
 	float4 f = kernel_tex_fetch(__particles, offset);
 	return f.x;
 }
 
-__device float particle_lifetime(KernelGlobals *kg, int particle)
+__device float particle_age(KernelGlobals *kg, int particle)
 {
 	int offset = particle*PARTICLE_SIZE;
 	float4 f = kernel_tex_fetch(__particles, offset);
 	return f.y;
 }
 
+__device float particle_lifetime(KernelGlobals *kg, int particle)
+{
+	int offset = particle*PARTICLE_SIZE;
+	float4 f = kernel_tex_fetch(__particles, offset);
+	return f.z;
+}
+
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/svm/svm_geometry.h b/intern/cycles/kernel/svm/svm_geometry.h
index 88127b56474..3cfce1d087a 100644
--- a/intern/cycles/kernel/svm/svm_geometry.h
+++ b/intern/cycles/kernel/svm/svm_geometry.h
@@ -101,6 +101,12 @@ __device void svm_node_particle_info(KernelGlobals *kg, ShaderData *sd, float *s
 	float data;
 
 	switch(type) {
+		case NODE_INFO_PAR_INDEX: {
+			uint particle_id = object_particle_id(kg, sd->object);
+			data = particle_index(kg, particle_id);
+			stack_store_float(stack, out_offset, data);
+			break;
+		}
 		case NODE_INFO_PAR_AGE: {
 			uint particle_id = object_particle_id(kg, sd->object);
 			data = particle_age(kg, particle_id);
diff --git a/intern/cycles/kernel/svm/svm_types.h b/intern/cycles/kernel/svm/svm_types.h
index c1eeeb55268..cbff0c099ea 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -114,6 +114,7 @@ typedef enum NodeObjectInfo {
 } NodeObjectInfo;
 
 typedef enum NodeParticleInfo {
+	NODE_INFO_PAR_INDEX,
 	NODE_INFO_PAR_AGE,
 	NODE_INFO_PAR_LIFETIME
 } NodeParticleInfo;
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index e4a4b874964..250570e1d65 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -1798,12 +1798,15 @@ void ObjectInfoNode::compile(OSLCompiler& compiler)
 ParticleInfoNode::ParticleInfoNode()
 : ShaderNode("particle_info")
 {
+	add_output("Index", SHADER_SOCKET_FLOAT);
 	add_output("Age", SHADER_SOCKET_FLOAT);
 	add_output("Lifetime", SHADER_SOCKET_FLOAT);
 }
 
 void ParticleInfoNode::attributes(AttributeRequestSet *attributes)
 {
+	if(!output("Index")->links.empty())
+		attributes->add(ATTR_STD_PARTICLE);
 	if(!output("Age")->links.empty())
 		attributes->add(ATTR_STD_PARTICLE);
 	if(!output("Lifetime")->links.empty())
@@ -1816,6 +1819,12 @@ void ParticleInfoNode::compile(SVMCompiler& compiler)
 {
 	ShaderOutput *out;
 	
+	out = output("Index");
+	if(!out->links.empty()) {
+		compiler.stack_assign(out);
+		compiler.add_node(NODE_PARTICLE_INFO, NODE_INFO_PAR_INDEX, out->stack_offset);
+	}
+	
 	out = output("Age");
 	if(!out->links.empty()) {
 		compiler.stack_assign(out);
diff --git a/intern/cycles/render/object.cpp b/intern/cycles/render/object.cpp
index 6de7eaea343..c4b25e633bf 100644
--- a/intern/cycles/render/object.cpp
+++ b/intern/cycles/render/object.cpp
@@ -269,7 +269,7 @@ void ObjectManager::device_update_particles(Device *device, DeviceScene *dscene,
 			/* pack in texture */
 			int offset = i*PARTICLE_SIZE;
 			
-			particles[offset] = make_float4(pa.age, pa.lifetime, 0.0f, 0.0f);
+			particles[offset] = make_float4(pa.index, pa.age, pa.lifetime, 0.0f);
 			
 			i++;
 			
diff --git a/intern/cycles/render/object.h b/intern/cycles/render/object.h
index 6d674731b07..9b2f5bc8768 100644
--- a/intern/cycles/render/object.h
+++ b/intern/cycles/render/object.h
@@ -36,6 +36,7 @@ struct Transform;
 /* Object */
 
 struct Particle {
+	int index;
 	float age;
 	float lifetime;
 };