Geometry Nodes: initial scattering and geometry nodes

This is the initial merge from the geometry-nodes branch.
Nodes:
* Attribute Math
* Boolean
* Edge Split
* Float Compare
* Object Info
* Point Distribute
* Point Instance
* Random Attribute
* Random Float
* Subdivision Surface
* Transform
* Triangulate

It includes the initial evaluation of geometry node groups in the Geometry Nodes modifier.

Notes on the Generic attribute access API

The API adds an indirection for attribute access. That has the following benefits:
* Most code does not have to care about how an attribute is stored internally.
  This is mainly necessary, because we have to deal with "legacy" attributes
  such as vertex weights and attributes that are embedded into other structs
  such as vertex positions.
* When reading from an attribute, we generally don't care what domain the
  attribute is stored on. So we want to abstract away the interpolation that
  that adapts attributes from one domain to another domain (this is not
  actually implemented yet).

Other possible improvements for later iterations include:
* Actually implement interpolation between domains.
* Don't use inheritance for the different attribute types. A single class for read
  access and one for write access might be enough, because we know all the ways
  in which attributes are stored internally. We don't want more different internal
  structures in the future. On the contrary, ideally we can consolidate the different
  storage formats in the future to reduce the need for this indirection.
* Remove the need for heap allocations when creating attribute accessors.

It includes commits from:
* Dalai Felinto
* Hans Goudey
* Jacques Lucke
* Léo Depoix

1 files changed, 200 insertions, 0 deletions

diff --git a/source/blender/nodes/NOD_math_functions.hh b/source/blender/nodes/NOD_math_functions.hh
new file mode 100644
index 00000000000..70e4174a844
--- /dev/null
+++ b/source/blender/nodes/NOD_math_functions.hh
@@ -0,0 +1,200 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include "DNA_node_types.h"
+
+#include "BLI_math_base_safe.h"
+#include "BLI_math_rotation.h"
+#include "BLI_string_ref.hh"
+
+namespace blender::nodes {
+
+struct FloatMathOperationInfo {
+  StringRefNull title_case_name;
+  StringRefNull shader_name;
+
+  FloatMathOperationInfo() = delete;
+  FloatMathOperationInfo(StringRefNull title_case_name, StringRefNull shader_name)
+      : title_case_name(title_case_name), shader_name(shader_name)
+  {
+  }
+};
+
+const FloatMathOperationInfo *get_float_math_operation_info(const int operation);
+
+/**
+ * This calls the `callback` with two arguments:
+ *  1. The math function that takes a float as input and outputs a new float.
+ *  2. A #FloatMathOperationInfo struct reference.
+ * Returns true when the callback has been called, otherwise false.
+ *
+ * The math function that is passed to the callback is actually a lambda function that is different
+ * for every operation. Therefore, if the callback is templated on the math function, it will get
+ * instantiated for every operation separately. This has two benefits:
+ *  - The compiler can optimize the callback for every operation separately.
+ *  - A static variable declared in the callback will be generated for every operation separately.
+ *
+ * If separate instantiations are not desired, the callback can also take a function pointer with
+ * the following signature as input instead: float (*math_function)(float a).
+ */
+template<typename Callback>
+inline bool try_dispatch_float_math_fl_to_fl(const int operation, Callback &&callback)
+{
+  const FloatMathOperationInfo *info = get_float_math_operation_info(operation);
+  if (info == nullptr) {
+    return false;
+  }
+
+  /* This is just an utility function to keep the individual cases smaller. */
+  auto dispatch = [&](auto math_function) -> bool {
+    callback(math_function, *info);
+    return true;
+  };
+
+  switch (operation) {
+    case NODE_MATH_EXPONENT:
+      return dispatch([](float a) { return expf(a); });
+    case NODE_MATH_SQRT:
+      return dispatch([](float a) { return safe_sqrtf(a); });
+    case NODE_MATH_INV_SQRT:
+      return dispatch([](float a) { return safe_inverse_sqrtf(a); });
+    case NODE_MATH_ABSOLUTE:
+      return dispatch([](float a) { return fabs(a); });
+    case NODE_MATH_RADIANS:
+      return dispatch([](float a) { return (float)DEG2RAD(a); });
+    case NODE_MATH_DEGREES:
+      return dispatch([](float a) { return (float)RAD2DEG(a); });
+    case NODE_MATH_SIGN:
+      return dispatch([](float a) { return compatible_signf(a); });
+    case NODE_MATH_ROUND:
+      return dispatch([](float a) { return floorf(a + 0.5f); });
+    case NODE_MATH_FLOOR:
+      return dispatch([](float a) { return floorf(a); });
+    case NODE_MATH_CEIL:
+      return dispatch([](float a) { return ceilf(a); });
+    case NODE_MATH_FRACTION:
+      return dispatch([](float a) { return a - floorf(a); });
+    case NODE_MATH_TRUNC:
+      return dispatch([](float a) { return a >= 0.0f ? floorf(a) : ceilf(a); });
+    case NODE_MATH_SINE:
+      return dispatch([](float a) { return sinf(a); });
+    case NODE_MATH_COSINE:
+      return dispatch([](float a) { return cosf(a); });
+    case NODE_MATH_TANGENT:
+      return dispatch([](float a) { return tanf(a); });
+    case NODE_MATH_SINH:
+      return dispatch([](float a) { return sinhf(a); });
+    case NODE_MATH_COSH:
+      return dispatch([](float a) { return coshf(a); });
+    case NODE_MATH_TANH:
+      return dispatch([](float a) { return tanhf(a); });
+    case NODE_MATH_ARCSINE:
+      return dispatch([](float a) { return safe_asinf(a); });
+    case NODE_MATH_ARCCOSINE:
+      return dispatch([](float a) { return safe_acosf(a); });
+    case NODE_MATH_ARCTANGENT:
+      return dispatch([](float a) { return atanf(a); });
+  }
+  return false;
+}
+
+/**
+ * This is similar to try_dispatch_float_math_fl_to_fl, just with a different callback signature.
+ */
+template<typename Callback>
+inline bool try_dispatch_float_math_fl_fl_to_fl(const int operation, Callback &&callback)
+{
+  const FloatMathOperationInfo *info = get_float_math_operation_info(operation);
+  if (info == nullptr) {
+    return false;
+  }
+
+  /* This is just an utility function to keep the individual cases smaller. */
+  auto dispatch = [&](auto math_function) -> bool {
+    callback(math_function, *info);
+    return true;
+  };
+
+  switch (operation) {
+    case NODE_MATH_ADD:
+      return dispatch([](float a, float b) { return a + b; });
+    case NODE_MATH_SUBTRACT:
+      return dispatch([](float a, float b) { return a - b; });
+    case NODE_MATH_MULTIPLY:
+      return dispatch([](float a, float b) { return a * b; });
+    case NODE_MATH_DIVIDE:
+      return dispatch([](float a, float b) { return safe_divide(a, b); });
+    case NODE_MATH_POWER:
+      return dispatch([](float a, float b) { return safe_powf(a, b); });
+    case NODE_MATH_LOGARITHM:
+      return dispatch([](float a, float b) { return safe_logf(a, b); });
+    case NODE_MATH_MINIMUM:
+      return dispatch([](float a, float b) { return std::min(a, b); });
+    case NODE_MATH_MAXIMUM:
+      return dispatch([](float a, float b) { return std::max(a, b); });
+    case NODE_MATH_LESS_THAN:
+      return dispatch([](float a, float b) { return (float)(a < b); });
+    case NODE_MATH_GREATER_THAN:
+      return dispatch([](float a, float b) { return (float)(a > b); });
+    case NODE_MATH_MODULO:
+      return dispatch([](float a, float b) { return safe_modf(a, b); });
+    case NODE_MATH_SNAP:
+      return dispatch([](float a, float b) { return floorf(safe_divide(a, b)) * b; });
+    case NODE_MATH_ARCTAN2:
+      return dispatch([](float a, float b) { return atan2f(a, b); });
+    case NODE_MATH_PINGPONG:
+      return dispatch([](float a, float b) { return pingpongf(a, b); });
+  }
+  return false;
+}
+
+/**
+ * This is similar to try_dispatch_float_math_fl_to_fl, just with a different callback signature.
+ */
+template<typename Callback>
+inline bool try_dispatch_float_math_fl_fl_fl_to_fl(const int operation, Callback &&callback)
+{
+  const FloatMathOperationInfo *info = get_float_math_operation_info(operation);
+  if (info == nullptr) {
+    return false;
+  }
+
+  /* This is just an utility function to keep the individual cases smaller. */
+  auto dispatch = [&](auto math_function) -> bool {
+    callback(math_function, *info);
+    return true;
+  };
+
+  switch (operation) {
+    case NODE_MATH_MULTIPLY_ADD:
+      return dispatch([](float a, float b, float c) { return a * b + c; });
+    case NODE_MATH_COMPARE:
+      return dispatch([](float a, float b, float c) -> float {
+        return ((a == b) || (fabsf(a - b) <= fmaxf(c, FLT_EPSILON))) ? 1.0f : 0.0f;
+      });
+    case NODE_MATH_SMOOTH_MIN:
+      return dispatch([](float a, float b, float c) { return smoothminf(a, b, c); });
+    case NODE_MATH_SMOOTH_MAX:
+      return dispatch([](float a, float b, float c) { return -smoothminf(-a, -b, -c); });
+    case NODE_MATH_WRAP:
+      return dispatch([](float a, float b, float c) { return wrapf(a, b, c); });
+  }
+  return false;
+}
+
+}  // namespace blender::nodes