Particle Info node for Cycles. This can be used to access particle information in material shaders for dupli objects. For now only the particle Age and individual Lifetime (in frames) are supported, more attributes can be added when needed.

The particle data is stored in a separate texture if any of the dupli objects uses particle info nodes in shaders. To map dupli objects onto particles the store an additional particle_index value, which is different from the simple dupli object index (only visible particles, also works for particle dupli groups mode).

Some simple use cases on the code.blender.org blog:
http://code.blender.org/index.php/2012/05/particle-info-node/

1 files changed, 43 insertions, 1 deletions

diff --git a/intern/cycles/render/object.cpp b/intern/cycles/render/object.cpp
index 5c7e48a38eb..259a0d25bcc 100644
--- a/intern/cycles/render/object.cpp
+++ b/intern/cycles/render/object.cpp
@@ -25,6 +25,7 @@
 #include "util_foreach.h"
 #include "util_map.h"
 #include "util_progress.h"
+#include "util_vector.h"
 
 CCL_NAMESPACE_BEGIN
 
@@ -38,6 +39,7 @@ Object::Object()
 	visibility = ~0;
 	random_id = 0;
 	pass_id = 0;
+	particle_id = 0;
 	bounds = BoundBox::empty;
 	motion.pre = transform_identity();
 	motion.post = transform_identity();
@@ -200,7 +202,7 @@ void ObjectManager::device_update_transforms(Device *device, DeviceScene *dscene
 
 		memcpy(&objects[offset], &tfm, sizeof(float4)*3);
 		memcpy(&objects[offset+3], &itfm, sizeof(float4)*3);
-		objects[offset+6] = make_float4(surface_area, pass_id, random_number, 0.0f);
+		objects[offset+6] = make_float4(surface_area, pass_id, random_number, __int_as_float(ob->particle_id));
 
 		if(need_motion == Scene::MOTION_PASS) {
 			/* motion transformations, is world/object space depending if mesh
@@ -246,6 +248,38 @@ void ObjectManager::device_update_transforms(Device *device, DeviceScene *dscene
 	device->tex_alloc("__object_flag", dscene->object_flag);
 }
 
+void ObjectManager::device_update_particles(Device *device, DeviceScene *dscene, Scene *scene, Progress& progress)
+{
+	/* count particles.
+	 * adds one dummy particle at the beginning to avoid invalid lookups,
+	 * in case a shader uses particle info without actual particle data.
+	 */
+	int num_particles = 1;
+	foreach(Object *ob, scene->objects)
+		num_particles += ob->particles.size();
+	
+	float4 *particles = dscene->particles.resize(PARTICLE_SIZE*num_particles);
+	
+	/* dummy particle */
+	particles[0] = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
+	
+	int i = 1;
+	foreach(Object *ob, scene->objects) {
+		foreach(Particle &pa, ob->particles) {
+			/* pack in texture */
+			int offset = i*PARTICLE_SIZE;
+			
+			particles[offset] = make_float4(pa.age, pa.lifetime, 0.0f, 0.0f);
+			
+			i++;
+			
+			if(progress.get_cancel()) return;
+		}
+	}
+	
+	device->tex_alloc("__particles", dscene->particles);
+}
+
 void ObjectManager::device_update(Device *device, DeviceScene *dscene, Scene *scene, Progress& progress)
 {
 	if(!need_update)
@@ -271,6 +305,11 @@ void ObjectManager::device_update(Device *device, DeviceScene *dscene, Scene *sc
 
 	if(progress.get_cancel()) return;
 
+	progress.set_status("Updating Objects", "Copying Particles to device");
+	device_update_particles(device, dscene, scene, progress);
+	
+	if(progress.get_cancel()) return;
+	
 	need_update = false;
 }
 
@@ -281,6 +320,9 @@ void ObjectManager::device_free(Device *device, DeviceScene *dscene)
 
 	device->tex_free(dscene->object_flag);
 	dscene->object_flag.clear();
+	
+	device->tex_free(dscene->particles);
+	dscene->particles.clear();
 }
 
 void ObjectManager::apply_static_transforms(Scene *scene, Progress& progress)