Eevee: Shadow map refactor

Reviewed By: brecht

Differential Revision: http://developer.blender.org/D5659

1 files changed, 111 insertions, 0 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_sampling.c b/source/blender/draw/engines/eevee/eevee_sampling.c
new file mode 100644
index 00000000000..9d91e000562
--- /dev/null
+++ b/source/blender/draw/engines/eevee/eevee_sampling.c
@@ -0,0 +1,111 @@
+/*
+ * 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.
+ *
+ * Copyright 2019, Blender Foundation.
+ */
+
+/** \file
+ * \ingroup EEVEE
+ */
+
+#include "eevee_private.h"
+
+#include "BLI_rand.h"
+
+/**
+ * Special ball distribution:
+ * Point are distributed in a way that when they are orthogonally
+ * projected into any plane, the resulting distribution is (close to)
+ * a uniform disc distribution.
+ */
+void EEVEE_sample_ball(int sample_ofs, float radius, float rsample[3])
+{
+  double ht_point[3];
+  double ht_offset[3] = {0.0, 0.0, 0.0};
+  uint ht_primes[3] = {2, 3, 7};
+
+  BLI_halton_3d(ht_primes, ht_offset, sample_ofs, ht_point);
+
+  float omega = ht_point[1] * 2.0f * M_PI;
+
+  rsample[2] = ht_point[0] * 2.0f - 1.0f; /* cos theta */
+
+  float r = sqrtf(fmaxf(0.0f, 1.0f - rsample[2] * rsample[2])); /* sin theta */
+
+  rsample[0] = r * cosf(omega);
+  rsample[1] = r * sinf(omega);
+
+  radius *= sqrt(sqrt(ht_point[2]));
+  mul_v3_fl(rsample, radius);
+}
+
+void EEVEE_sample_rectangle(int sample_ofs,
+                            const float x_axis[3],
+                            const float y_axis[3],
+                            float size_x,
+                            float size_y,
+                            float rsample[3])
+{
+  double ht_point[2];
+  double ht_offset[2] = {0.0, 0.0};
+  uint ht_primes[2] = {2, 3};
+
+  BLI_halton_2d(ht_primes, ht_offset, sample_ofs, ht_point);
+
+  /* Change ditribution center to be 0,0 */
+  ht_point[0] = (ht_point[0] > 0.5f) ? ht_point[0] - 1.0f : ht_point[0];
+  ht_point[1] = (ht_point[1] > 0.5f) ? ht_point[1] - 1.0f : ht_point[1];
+
+  zero_v3(rsample);
+  madd_v3_v3fl(rsample, x_axis, (ht_point[0] * 2.0f) * size_x);
+  madd_v3_v3fl(rsample, y_axis, (ht_point[1] * 2.0f) * size_y);
+}
+
+void EEVEE_sample_ellipse(int sample_ofs,
+                          const float x_axis[3],
+                          const float y_axis[3],
+                          float size_x,
+                          float size_y,
+                          float rsample[3])
+{
+  double ht_point[2];
+  double ht_offset[2] = {0.0, 0.0};
+  uint ht_primes[2] = {2, 3};
+
+  BLI_halton_2d(ht_primes, ht_offset, sample_ofs, ht_point);
+
+  /* Uniform disc sampling. */
+  float omega = ht_point[1] * 2.0f * M_PI;
+  float r = sqrtf(ht_point[0]);
+  ht_point[0] = r * cosf(omega) * size_x;
+  ht_point[1] = r * sinf(omega) * size_y;
+
+  zero_v3(rsample);
+  madd_v3_v3fl(rsample, x_axis, ht_point[0]);
+  madd_v3_v3fl(rsample, y_axis, ht_point[1]);
+}
+
+void EEVEE_random_rotation_m4(int sample_ofs, float scale, float r_mat[4][4])
+{
+  double ht_point[3];
+  double ht_offset[3] = {0.0, 0.0, 0.0};
+  uint ht_primes[3] = {2, 3, 5};
+
+  BLI_halton_3d(ht_primes, ht_offset, sample_ofs, ht_point);
+
+  rotate_m4(r_mat, 'X', ht_point[0] * scale);
+  rotate_m4(r_mat, 'Y', ht_point[1] * scale);
+  rotate_m4(r_mat, 'Z', ht_point[2] * scale);
+}
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