Realtime Compositor: Implement Tone Map node

This patch implements the tone map node for the realtime compositor
based on the two papers:

Reinhard, Erik, et al. "Photographic tone reproduction for digital
images." Proceedings of the 29th annual conference on Computer graphics
and interactive techniques. 2002.

Reinhard, Erik, and Kate Devlin. "Dynamic range reduction inspired by
photoreceptor physiology." IEEE transactions on visualization and
computer graphics 11.1 (2005): 13-24.

The original implementation should be revisited later due to apparent
incompatibilities with the reference papers, which makes the operation
less useful.

Differential Revision: https://developer.blender.org/D16306

Reviewed By: Clement Foucault

5 files changed, 130 insertions, 4 deletions

diff --git a/source/blender/gpu/shaders/compositor/compositor_tone_map_photoreceptor.glsl b/source/blender/gpu/shaders/compositor/compositor_tone_map_photoreceptor.glsl
new file mode 100644
index 00000000000..167006585ca
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/compositor_tone_map_photoreceptor.glsl
@@ -0,0 +1,22 @@
+#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl)
+
+/* Tone mapping based on equation (1) and the trilinear interpolation between equations (6) and (7)
+ * from Reinhard, Erik, and Kate Devlin. "Dynamic range reduction inspired by photoreceptor
+ * physiology." IEEE transactions on visualization and computer graphics 11.1 (2005): 13-24. */
+void main()
+{
+  ivec2 texel = ivec2(gl_GlobalInvocationID.xy);
+
+  vec4 input_color = texture_load(input_tx, texel);
+  float input_luminance = dot(input_color.rgb, luminance_coefficients);
+
+  /* Trilinear interpolation between equations (6) and (7) from Reinhard's 2005 paper. */
+  vec4 local_adaptation_level = mix(vec4(input_luminance), input_color, chromatic_adaptation);
+  vec4 adaptation_level = mix(global_adaptation_level, local_adaptation_level, light_adaptation);
+
+  /* Equation (1) from Reinhard's 2005 paper, assuming Vmax is 1. */
+  vec4 semi_saturation = pow(intensity * adaptation_level, vec4(contrast));
+  vec4 tone_mapped_color = input_color / (input_color + semi_saturation);
+
+  imageStore(output_img, texel, vec4(tone_mapped_color.rgb, input_color.a));
+}
diff --git a/source/blender/gpu/shaders/compositor/compositor_tone_map_simple.glsl b/source/blender/gpu/shaders/compositor/compositor_tone_map_simple.glsl
new file mode 100644
index 00000000000..ce42d021dd1
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/compositor_tone_map_simple.glsl
@@ -0,0 +1,26 @@
+#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl)
+#pragma BLENDER_REQUIRE(gpu_shader_common_math_utils.glsl)
+
+/* Tone mapping based on equation (3) from Reinhard, Erik, et al. "Photographic tone reproduction
+ * for digital images." Proceedings of the 29th annual conference on Computer graphics and
+ * interactive techniques. 2002. */
+void main()
+{
+  ivec2 texel = ivec2(gl_GlobalInvocationID.xy);
+
+  vec4 input_color = texture_load(input_tx, texel);
+
+  /* Equation (2) from Reinhard's 2002 paper. */
+  vec4 scaled_color = input_color * luminance_scale;
+
+  /* Equation (3) from Reinhard's 2002 paper, but with the 1 replaced with the blend factor for
+   * more flexibility. See ToneMapOperation::compute_luminance_scale_blend_factor. */
+  vec4 denominator = luminance_scale_blend_factor + scaled_color;
+  vec4 tone_mapped_color = safe_divide(scaled_color, denominator);
+
+  if (inverse_gamma != 0.0) {
+    tone_mapped_color = pow(max(tone_mapped_color, vec4(0.0)), vec4(inverse_gamma));
+  }
+
+  imageStore(output_img, texel, vec4(tone_mapped_color.rgb, input_color.a));
+}
diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_parallel_reduction_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_parallel_reduction_info.hh
index 2e661f280af..4a71bdc80e2 100644
--- a/source/blender/gpu/shaders/compositor/infos/compositor_parallel_reduction_info.hh
+++ b/source/blender/gpu/shaders/compositor/infos/compositor_parallel_reduction_info.hh
@@ -12,14 +12,17 @@ GPU_SHADER_CREATE_INFO(compositor_parallel_reduction_shared)
  * Sum Reductions.
  */
 
-GPU_SHADER_CREATE_INFO(compositor_sum_float_shared)
+GPU_SHADER_CREATE_INFO(compositor_sum_shared)
     .additional_info("compositor_parallel_reduction_shared")
-    .image(0, GPU_R32F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
-    .define("TYPE", "float")
     .define("IDENTITY", "vec4(0.0)")
-    .define("LOAD(value)", "value.x")
     .define("REDUCE(lhs, rhs)", "lhs + rhs");
 
+GPU_SHADER_CREATE_INFO(compositor_sum_float_shared)
+    .additional_info("compositor_sum_shared")
+    .image(0, GPU_R32F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .define("TYPE", "float")
+    .define("LOAD(value)", "value.x");
+
 GPU_SHADER_CREATE_INFO(compositor_sum_red)
     .additional_info("compositor_sum_float_shared")
     .define("INITIALIZE(value)", "value.r")
@@ -41,6 +44,20 @@ GPU_SHADER_CREATE_INFO(compositor_sum_luminance)
     .define("INITIALIZE(value)", "dot(value.rgb, luminance_coefficients)")
     .do_static_compilation(true);
 
+GPU_SHADER_CREATE_INFO(compositor_sum_log_luminance)
+    .additional_info("compositor_sum_float_shared")
+    .push_constant(Type::VEC3, "luminance_coefficients")
+    .define("INITIALIZE(value)", "log(max(dot(value.rgb, luminance_coefficients), 1e-5))")
+    .do_static_compilation(true);
+
+GPU_SHADER_CREATE_INFO(compositor_sum_color)
+    .additional_info("compositor_sum_shared")
+    .image(0, GPU_RGBA32F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .define("TYPE", "vec4")
+    .define("INITIALIZE(value)", "value")
+    .define("LOAD(value)", "value")
+    .do_static_compilation(true);
+
 /* --------------------------------------------------------------------
  * Sum Of Squared Difference Reductions.
  */
@@ -74,3 +91,35 @@ GPU_SHADER_CREATE_INFO(compositor_sum_luminance_squared_difference)
     .push_constant(Type::VEC3, "luminance_coefficients")
     .define("INITIALIZE(value)", "pow(dot(value.rgb, luminance_coefficients) - subtrahend, 2.0)")
     .do_static_compilation(true);
+
+/* --------------------------------------------------------------------
+ * Maximum Reductions.
+ */
+
+GPU_SHADER_CREATE_INFO(compositor_maximum_luminance)
+    .additional_info("compositor_parallel_reduction_shared")
+    .typedef_source("common_math_lib.glsl")
+    .image(0, GPU_R32F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .push_constant(Type::VEC3, "luminance_coefficients")
+    .define("TYPE", "float")
+    .define("IDENTITY", "vec4(FLT_MIN)")
+    .define("INITIALIZE(value)", "dot(value.rgb, luminance_coefficients)")
+    .define("LOAD(value)", "value.x")
+    .define("REDUCE(lhs, rhs)", "max(lhs, rhs)")
+    .do_static_compilation(true);
+
+/* --------------------------------------------------------------------
+ * Minimum Reductions.
+ */
+
+GPU_SHADER_CREATE_INFO(compositor_minimum_luminance)
+    .additional_info("compositor_parallel_reduction_shared")
+    .typedef_source("common_math_lib.glsl")
+    .image(0, GPU_R32F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .push_constant(Type::VEC3, "luminance_coefficients")
+    .define("TYPE", "float")
+    .define("IDENTITY", "vec4(FLT_MAX)")
+    .define("INITIALIZE(value)", "dot(value.rgb, luminance_coefficients)")
+    .define("LOAD(value)", "value.x")
+    .define("REDUCE(lhs, rhs)", "min(lhs, rhs)")
+    .do_static_compilation(true);
diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_photoreceptor_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_photoreceptor_info.hh
new file mode 100644
index 00000000000..a460c9d58a6
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_photoreceptor_info.hh
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "gpu_shader_create_info.hh"
+
+GPU_SHADER_CREATE_INFO(compositor_tone_map_photoreceptor)
+    .local_group_size(16, 16)
+    .push_constant(Type::VEC4, "global_adaptation_level")
+    .push_constant(Type::FLOAT, "contrast")
+    .push_constant(Type::FLOAT, "intensity")
+    .push_constant(Type::FLOAT, "chromatic_adaptation")
+    .push_constant(Type::FLOAT, "light_adaptation")
+    .push_constant(Type::VEC3, "luminance_coefficients")
+    .sampler(0, ImageType::FLOAT_2D, "input_tx")
+    .image(0, GPU_RGBA16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .compute_source("compositor_tone_map_photoreceptor.glsl")
+    .do_static_compilation(true);
diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_simple_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_simple_info.hh
new file mode 100644
index 00000000000..2b220af9460
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/infos/compositor_tone_map_simple_info.hh
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "gpu_shader_create_info.hh"
+
+GPU_SHADER_CREATE_INFO(compositor_tone_map_simple)
+    .local_group_size(16, 16)
+    .push_constant(Type::FLOAT, "luminance_scale")
+    .push_constant(Type::FLOAT, "luminance_scale_blend_factor")
+    .push_constant(Type::FLOAT, "inverse_gamma")
+    .sampler(0, ImageType::FLOAT_2D, "input_tx")
+    .image(0, GPU_RGBA16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img")
+    .compute_source("compositor_tone_map_simple.glsl")
+    .do_static_compilation(true);