node_composite_chroma_matte.cc

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/* SPDX-FileCopyrightText: 2006 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
#include <cmath>
 
#include "BLI_math_base.hh"
#include "BLI_math_color.h"
#include "BLI_math_matrix.hh"
#include "BLI_math_rotation.h"
#include "BLI_math_vector_types.hh"
 
#include "FN_multi_function_builder.hh"
 
#include "NOD_multi_function.hh"
 
#include "UI_interface.hh"
#include "UI_resources.hh"
 
#include "GPU_material.hh"
 
#include "node_composite_util.hh"
 
/* ******************* Chroma Key ********************************************************** */
 
namespace blender::nodes::node_composite_chroma_matte_cc {
 
static void cmp_node_chroma_matte_declare(NodeDeclarationBuilder &b)
{
  b.add_input<decl::Color>("Image").default_value({1.0f, 1.0f, 1.0f, 1.0f});
  b.add_input<decl::Color>("Key Color").default_value({1.0f, 1.0f, 1.0f, 1.0f});
  b.add_input<decl::Float>("Minimum")
      .default_value(DEG2RADF(10.0f))
      .subtype(PROP_ANGLE)
      .description(
          "If the angle between the color and the key color in CrCb space is less than this "
          "minimum angle, it is keyed");
  b.add_input<decl::Float>("Maximum")
      .default_value(DEG2RADF(30.0f))
      .subtype(PROP_ANGLE)
      .description(
          "If the angle between the color and the key color in CrCb space is larger than this "
          "maximum angle, it is not keyed");
  b.add_input<decl::Float>("Falloff")
      .default_value(1.0f)
      .min(0.0f)
      .max(1.0f)
      .subtype(PROP_FACTOR)
      .description(
          "Controls the falloff between keyed and non-keyed values. 0 means completely sharp and "
          "1 means completely smooth");
 
  b.add_output<decl::Color>("Image");
  b.add_output<decl::Float>("Matte");
}
 
using namespace blender::compositor;
 
static int node_gpu_material(GPUMaterial *material,
                             bNode *node,
                             bNodeExecData * /*execdata*/,
                             GPUNodeStack *inputs,
                             GPUNodeStack *outputs)
{
  return GPU_stack_link(material, node, "node_composite_chroma_matte", inputs, outputs);
}
 
/* Algorithm from the book Video Demystified. Chapter 7. Chroma Keying. */
static void chroma_matte(const float4 &color,
                         const float4 &key,
                         const float &minimum,
                         const float &maximum,
                         const float &falloff,
                         float4 &result,
                         float &matte)
{
  float3 color_ycca;
  rgb_to_ycc(
      color.x, color.y, color.z, &color_ycca.x, &color_ycca.y, &color_ycca.z, BLI_YCC_ITU_BT709);
  color_ycca /= 255.0f;
  float3 key_ycca;
  rgb_to_ycc(key.x, key.y, key.z, &key_ycca.x, &key_ycca.y, &key_ycca.z, BLI_YCC_ITU_BT709);
  key_ycca /= 255.0f;
 
  /* Normalize the CrCb components into the [-1, 1] range. */
  float2 color_cc = color_ycca.yz() * 2.0f - 1.0f;
  float2 key_cc = math::normalize(key_ycca.yz() * 2.0f - 1.0f);
 
  /* Rotate the color onto the space of the key such that x axis of the color space passes
   * through the key color. */
  color_cc = math::from_direction(key_cc * float2(1.0f, -1.0f)) * color_cc;
 
  /* Compute foreground key. If positive, the value is in the [0, 1] range. */
  float foreground_key = color_cc.x - (math::abs(color_cc.y) / math::tan(maximum / 2.0f));
 
  /* Negative foreground key values retain the original alpha. Positive values are scaled by the
   * falloff, while colors that make an angle less than the minimum angle get a zero alpha. */
  float alpha = color.w;
  if (foreground_key > 0.0f) {
    alpha = 1.0f - (foreground_key / falloff);
 
    if (math::abs(math::atan2(color_cc.y, color_cc.x)) < (minimum / 2.0f)) {
      alpha = 0.0f;
    }
  }
 
  /* Compute output. */
  matte = math::min(alpha, color.w);
  result = color * matte;
}
 
static void node_build_multi_function(blender::nodes::NodeMultiFunctionBuilder &builder)
{
  builder.construct_and_set_matching_fn_cb([=]() {
    return mf::build::SI5_SO2<float4, float4, float, float, float, float4, float>(
        "Chroma Key",
        [=](const float4 &color,
            const float4 &key_color,
            const float &minimum,
            const float &maximum,
            const float &falloff,
            float4 &output_color,
            float &matte) -> void {
          chroma_matte(color, key_color, minimum, maximum, falloff, output_color, matte);
        },
        mf::build::exec_presets::SomeSpanOrSingle<0, 1>());
  });
}
 
}  // namespace blender::nodes::node_composite_chroma_matte_cc
 
static void register_node_type_cmp_chroma_matte()
{
  namespace file_ns = blender::nodes::node_composite_chroma_matte_cc;
 
  static blender::bke::bNodeType ntype;
 
  cmp_node_type_base(&ntype, "CompositorNodeChromaMatte", CMP_NODE_CHROMA_MATTE);
  ntype.ui_name = "Chroma Key";
  ntype.ui_description = "Create matte based on chroma values";
  ntype.enum_name_legacy = "CHROMA_MATTE";
  ntype.nclass = NODE_CLASS_MATTE;
  ntype.declare = file_ns::cmp_node_chroma_matte_declare;
  ntype.flag |= NODE_PREVIEW;
  ntype.gpu_fn = file_ns::node_gpu_material;
  ntype.build_multi_function = file_ns::node_build_multi_function;
 
  blender::bke::node_register_type(ntype);
}
NOD_REGISTER_NODE(register_node_type_cmp_chroma_matte)