COM_context.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include "BLI_math_vector_types.hh"
#include "BLI_string_ref.hh"
 
#include "DNA_ID.h"
#include "DNA_scene_types.h"
#include "DNA_vec_types.h"
 
#include "GPU_shader.hh"
#include "GPU_texture.hh"
 
#include "COM_domain.hh"
#include "COM_meta_data.hh"
#include "COM_profiler.hh"
#include "COM_render_context.hh"
#include "COM_result.hh"
#include "COM_static_cache_manager.hh"
#include "COM_texture_pool.hh"
 
namespace blender::realtime_compositor {
 
/* ------------------------------------------------------------------------------------------------
 * Context
 *
 * A Context is an abstract class that is implemented by the caller of the evaluator to provide the
 * necessary data and functionalities for the correct operation of the evaluator. This includes
 * providing input data like render passes and the active scene, as well as references to the data
 * where the output of the evaluator will be written. The class also provides a reference to the
 * texture pool which should be implemented by the caller and provided during construction.
 * Finally, the class have an instance of a static resource manager for acquiring cached resources
 * efficiently. */
class Context {
 private:
  /* A texture pool that can be used to allocate textures for the compositor efficiently. */
  TexturePool &texture_pool_;
  /* A static cache manager that can be used to acquire cached resources for the compositor
   * efficiently. */
  StaticCacheManager cache_manager_;
 
 public:
  Context(TexturePool &texture_pool);
 
  /* Get the compositing scene. */
  virtual const Scene &get_scene() const = 0;
 
  /* Get the node tree used for compositing. */
  virtual const bNodeTree &get_node_tree() const = 0;
 
  /* True if the compositor should use GPU acceleration. */
  virtual bool use_gpu() const = 0;
 
  /* True if the compositor should write file outputs, false otherwise. */
  virtual bool use_file_output() const = 0;
 
  /* True if the compositor should compute node previews, false otherwise. */
  virtual bool should_compute_node_previews() const = 0;
 
  /* True if the compositor should write the composite output, otherwise, the compositor is assumed
   * to not support the composite output and just displays its viewer output. In that case, the
   * composite output will be used as a fallback viewer if no other viewer exists */
  virtual bool use_composite_output() const = 0;
 
  /* Get the render settings for compositing. */
  virtual const RenderData &get_render_data() const = 0;
 
  /* Get the width and height of the render passes and of the output texture returned by the
   * get_input_texture and get_output_texture methods respectively. */
  virtual int2 get_render_size() const = 0;
 
  /* Get the rectangular region representing the area of the input that the compositor will operate
   * on. Conversely, the compositor will only update the region of the output that corresponds to
   * the compositing region. In the base case, the compositing region covers the entirety of the
   * render region with a lower bound of zero and an upper bound of the render size returned by the
   * get_render_size method. In other cases, the compositing region might be a subset of the render
   * region. Callers should check the validity of the region through is_valid_compositing_region(),
   * since the region can be zero sized. */
  virtual rcti get_compositing_region() const = 0;
 
  /* Get the result where the result of the compositor should be written. */
  virtual Result get_output_result() = 0;
 
  /* Get the result where the result of the compositor viewer should be written, given the domain
   * of the result to be viewed, its precision, and whether the output is a non-color data image
   * that should be displayed without view transform. */
  virtual Result get_viewer_output_result(Domain domain,
                                          bool is_data,
                                          ResultPrecision precision) = 0;
 
  /* Get the texture where the given render pass is stored. This should be called by the Render
   * Layer node to populate its outputs. */
  virtual GPUTexture *get_input_texture(const Scene *scene,
                                        int view_layer,
                                        const char *pass_name) = 0;
 
  /* Get the name of the view currently being rendered. */
  virtual StringRef get_view_name() const = 0;
 
  /* Get the precision of the intermediate results of the compositor. */
  virtual ResultPrecision get_precision() const = 0;
 
  /* Set an info message. This is called by the compositor evaluator to inform or warn the user
   * about something, typically an error. The implementation should display the message in an
   * appropriate place, which can be directly in the UI or just logged to the output stream. */
  virtual void set_info_message(StringRef message) const = 0;
 
  /* Returns the ID recalculate flag of the given ID and reset it to zero. The given ID is assumed
   * to be one that has a DrawDataList and conforms to the IdDdtTemplate.
   *
   * The ID recalculate flag is a mechanism through which one can identify if an ID has changed
   * since the last time the flag was reset, hence why the method reset the flag after querying it,
   * that is, to ready it to track the next change. */
  virtual IDRecalcFlag query_id_recalc_flag(ID *id) const = 0;
 
  /* Populates the given meta data from the render stamp information of the given render pass. */
  virtual void populate_meta_data_for_pass(const Scene *scene,
                                           int view_layer_id,
                                           const char *pass_name,
                                           MetaData &meta_data) const;
 
  /* Get a pointer to the render context of this context. A render context stores information about
   * the current render. It might be null if the compositor is not being evaluated as part of a
   * render pipeline. */
  virtual RenderContext *render_context() const;
 
  /* Get a pointer to the profiler of this context. It might be null if the compositor context does
   * not support profiling. */
  virtual Profiler *profiler() const;
 
  /* Gets called after the evaluation of each compositor operation. See overrides for possible
   * uses. */
  virtual void evaluate_operation_post() const;
 
  /* Returns true if the compositor evaluation is canceled and that the evaluator should stop
   * executing as soon as possible. */
  virtual bool is_canceled() const;
 
  /* Resets the context's internal structures like texture pool and cache manager. This should be
   * called before every evaluation. */
  void reset();
 
  /* Get the size of the compositing region. See get_compositing_region(). The output size is
   * sanitized such that it is at least 1 in both dimensions. However, the developer is expected to
   * gracefully handled zero sizes regions by checking the is_valid_compositing_region method. */
  int2 get_compositing_region_size() const;
 
  /* Returns true if the compositing region has a valid size, that is, has at least one pixel in
   * both dimensions, returns false otherwise. */
  bool is_valid_compositing_region() const;
 
  /* Get the normalized render percentage of the active scene. */
  float get_render_percentage() const;
 
  /* Get the current frame number of the active scene. */
  int get_frame_number() const;
 
  /* Get the current time in seconds of the active scene. */
  float get_time() const;
 
  /* Get a GPU shader with the given info name and precision. */
  GPUShader *get_shader(const char *info_name, ResultPrecision precision);
 
  /* Get a GPU shader with the given info name and context's precision. */
  GPUShader *get_shader(const char *info_name);
 
  /* Create a result of the given type and precision. */
  Result create_result(ResultType type, ResultPrecision precision);
 
  /* Create a result of the given type using the context's precision. */
  Result create_result(ResultType type);
 
  /* Get a reference to the texture pool of this context. */
  TexturePool &texture_pool();
 
  /* Get a reference to the static cache manager of this context. */
  StaticCacheManager &cache_manager();
};
 
}  // namespace blender::realtime_compositor