Particles: new Age Reached Event, Kill Particle and Random Float node

The hardcoded age limit is now gone. The behavior can be implemented
with an Age Reached Event and Kill Particle node. Other utility nodes
to handle age limits of particles can be added later. Adding an
Age Limit attribute to particles on birth will be useful for some effects,
e.g. when you want to control the color or size of a particle over its
life time.

The Random Float node takes a seed currently. Different nodes will
produce different values even with the same seed. However, the same
node will generate the same random number for the same seed every
time. The "Hash" of a particle can be used as seed. Later, we'd want
to have more modes in the node to make it more user friendly.
Modes could be: Per Particle, Per Time, Per Particle Per Time,
Per Node Instance, ...
Also a Random Vector node will be useful, as it currently has to be
build using three Random Float nodes.

1 files changed, 89 insertions, 0 deletions

diff --git a/source/blender/nodes/function/nodes/node_fn_random_float.cc b/source/blender/nodes/function/nodes/node_fn_random_float.cc
new file mode 100644
index 00000000000..2ee0830637a
--- /dev/null
+++ b/source/blender/nodes/function/nodes/node_fn_random_float.cc
@@ -0,0 +1,89 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "node_function_util.hh"
+
+#include "BLI_hash.h"
+
+static bNodeSocketTemplate fn_node_random_float_in[] = {
+    {SOCK_FLOAT, N_("Min"), 0.0f, 0.0f, 0.0f, 0.0f, -10000.0f, 10000.0f, PROP_NONE},
+    {SOCK_FLOAT, N_("Max"), 1.0f, 0.0f, 0.0f, 0.0f, -10000.0f, 10000.0f, PROP_NONE},
+    {SOCK_INT, N_("Seed")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate fn_node_random_float_out[] = {
+    {SOCK_FLOAT, N_("Value")},
+    {-1, ""},
+};
+
+class RandomFloatFunction : public blender::fn::MultiFunction {
+ private:
+  uint32_t function_seed_;
+
+ public:
+  RandomFloatFunction(uint32_t function_seed) : function_seed_(function_seed)
+  {
+    blender::fn::MFSignatureBuilder signature = this->get_builder("Random float");
+    signature.single_input<float>("Min");
+    signature.single_input<float>("Max");
+    signature.single_input<int>("Seed");
+    signature.single_output<float>("Value");
+  }
+
+  void call(blender::IndexMask mask,
+            blender::fn::MFParams params,
+            blender::fn::MFContext UNUSED(context)) const override
+  {
+    blender::fn::VSpan<float> min_values = params.readonly_single_input<float>(0, "Min");
+    blender::fn::VSpan<float> max_values = params.readonly_single_input<float>(1, "Max");
+    blender::fn::VSpan<int> seeds = params.readonly_single_input<int>(2, "Seed");
+    blender::MutableSpan<float> values = params.uninitialized_single_output<float>(3, "Value");
+
+    for (int64_t i : mask) {
+      const float min_value = min_values[i];
+      const float max_value = max_values[i];
+      const int seed = seeds[i];
+      const float value = BLI_hash_int_01((uint32_t)seed ^ function_seed_);
+      values[i] = value * (max_value - min_value) + min_value;
+    }
+  }
+};
+
+static void fn_node_random_float_expand_in_mf_network(
+    blender::nodes::NodeMFNetworkBuilder &builder)
+{
+  uint32_t function_seed = 1746872341u;
+  const blender::nodes::DNode &node = builder.dnode();
+  const blender::DefaultHash<blender::StringRefNull> hasher;
+  function_seed = 33 * function_seed + hasher(node.name());
+  for (const blender::nodes::DParentNode *parent = node.parent(); parent != nullptr;
+       parent = parent->parent()) {
+    function_seed = 33 * function_seed + hasher(parent->node_ref().name());
+  }
+
+  builder.construct_and_set_matching_fn<RandomFloatFunction>(function_seed);
+}
+
+void register_node_type_fn_random_float()
+{
+  static bNodeType ntype;
+
+  fn_node_type_base(&ntype, FN_NODE_RANDOM_FLOAT, "Random Float", 0, 0);
+  node_type_socket_templates(&ntype, fn_node_random_float_in, fn_node_random_float_out);
+  ntype.expand_in_mf_network = fn_node_random_float_expand_in_mf_network;
+  nodeRegisterType(&ntype);
+}