path: root/game/addons/zylann.hterrain/tools/brush/painter.gd

# Core logic to paint a texture using shaders, with undo/redo support.
# Operations are delayed so results are only available the next frame.
# This doesn't implement UI or brush behavior, only rendering logic.
#
# Note: due to the absence of channel separation function in Image,
# you may need to use multiple painters at once if your application exploits multiple channels.
# Example: when painting a heightmap, it would be doable to output height in R, normalmap in GB, and
# then separate channels in two images at the end.

@tool
extends Node

const HT_Logger = preload("../../util/logger.gd")
const HT_Util = preload("../../util/util.gd")
const HT_NoBlendShader = preload("./no_blend.gdshader")
const HT_NoBlendRFShader = preload("./no_blend_rf.gdshader")

const UNDO_CHUNK_SIZE = 64

# All painting shaders can use these common parameters
const SHADER_PARAM_SRC_TEXTURE = "u_src_texture"
const SHADER_PARAM_SRC_RECT = "u_src_rect"
const SHADER_PARAM_OPACITY = "u_opacity"

const _API_SHADER_PARAMS = [
   SHADER_PARAM_SRC_TEXTURE,
   SHADER_PARAM_SRC_RECT,
   SHADER_PARAM_OPACITY
]

# Emitted when a region of the painted texture actually changed.
# Note 1: the image might not have changed yet at this point.
# Note 2: the user could still be in the middle of dragging the brush.
signal texture_region_changed(rect)

# Godot doesn't support 32-bit float rendering, so painting is limited to 16-bit depth.
# We should get this in Godot 4.0, either as Compute or renderer improvement
const _hdr_formats = [
   Image.FORMAT_RH,
   Image.FORMAT_RGH,
   Image.FORMAT_RGBH,
   Image.FORMAT_RGBAH
]

const _supported_formats = [
   Image.FORMAT_R8,
   Image.FORMAT_RG8,
   Image.FORMAT_RGB8,
   Image.FORMAT_RGBA8
   # No longer supported since Godot 4 removed support for it in 2D viewports...
#  Image.FORMAT_RH,
#  Image.FORMAT_RGH,
#  Image.FORMAT_RGBH,
#  Image.FORMAT_RGBAH
]

# - SubViewport (size of edited region + margin to allow quad rotation)
#   |- Background
#   |    Fills pixels with unmodified source image.
#   |- Brush sprite
#        Size of actual brush, scaled/rotated, modifies source image.
#        Assigned texture is the brush texture, src image is a shader param

var _viewport : SubViewport
var _viewport_bg_sprite : Sprite2D
var _viewport_brush_sprite : Sprite2D
var _brush_size := 32
var _brush_scale := 1.0
var _brush_position := Vector2()
var _brush_opacity := 1.0
var _brush_texture : Texture
var _last_brush_position := Vector2()
var _brush_material := ShaderMaterial.new()
var _no_blend_material : ShaderMaterial
var _image : Image
var _texture : ImageTexture
var _cmd_paint := false
var _pending_paint_render := false
var _modified_chunks := {}
var _modified_shader_params := {}

var _debug_display : TextureRect
var _logger = HT_Logger.get_for(self)


func _init():
   _viewport = SubViewport.new()
   _viewport.size = Vector2(_brush_size, _brush_size)
   _viewport.render_target_update_mode = SubViewport.UPDATE_ONCE
   _viewport.render_target_clear_mode = SubViewport.CLEAR_MODE_ONCE
   #_viewport.hdr = false
   # Require 4 components (RGBA)
   _viewport.transparent_bg = true
   # Apparently HDR doesn't work if this is set to 2D... so let's waste a depth buffer :/
   #_viewport.usage = Viewport.USAGE_2D
   #_viewport.keep_3d_linear
   
   # There is no "blend_disabled" option on standard CanvasItemMaterial...
   _no_blend_material = ShaderMaterial.new()
   _no_blend_material.shader = HT_NoBlendShader
   _viewport_bg_sprite = Sprite2D.new()
   _viewport_bg_sprite.centered = false
   _viewport_bg_sprite.material = _no_blend_material
   _viewport.add_child(_viewport_bg_sprite)
   
   _viewport_brush_sprite = Sprite2D.new()
   _viewport_brush_sprite.centered = true
   _viewport_brush_sprite.material = _brush_material
   _viewport_brush_sprite.position = _viewport.size / 2.0
   _viewport.add_child(_viewport_brush_sprite)
   
   add_child(_viewport)


func set_debug_display(dd: TextureRect):
   _debug_display = dd
   _debug_display.texture = _viewport.get_texture()


func set_image(image: Image, texture: ImageTexture):
   assert((image == null and texture == null) or (image != null and texture != null))
   _image = image
   _texture = texture
   _viewport_bg_sprite.texture = _texture
   _brush_material.set_shader_parameter(SHADER_PARAM_SRC_TEXTURE, _texture)
   if image != null:
      if image.get_format() == Image.FORMAT_RF:
         # In case of RF all shaders must encode their fragment outputs in RGBA8,
         # including the unmodified background, as Godot 4.0 does not support RF viewports
         _no_blend_material.shader = HT_NoBlendRFShader
      else:
         _no_blend_material.shader = HT_NoBlendShader
      # TODO HDR is required in order to paint heightmaps.
      # Seems Godot 4.0 does not support it, so we have to wait for Godot 4.1...
      #_viewport.hdr = image.get_format() in _hdr_formats
      if (image.get_format() in _hdr_formats) and image.get_format() != Image.FORMAT_RF:
         push_error("Godot 4.0 does not support HDR viewports for GPU-editing heightmaps! " +
            "Only RF is supported using a bit packing hack.")
   #print("PAINTER VIEWPORT HDR: ", _viewport.hdr)


# Sets the size of the brush in pixels.
# This will cause the internal viewport to resize, which is expensive.
# If you need to frequently change brush size during a paint stroke, prefer using scale instead.
func set_brush_size(new_size: int):
   _brush_size = new_size


func get_brush_size() -> int:
   return _brush_size


func set_brush_rotation(rotation: float):
   _viewport_brush_sprite.rotation = rotation


func get_brush_rotation() -> float:
   return _viewport_bg_sprite.rotation


# The difference between size and scale, is that size is in pixels, while scale is a multiplier.
# Scale is also a lot cheaper to change, so you may prefer changing it instead of size if that
# happens often during a painting stroke.
func set_brush_scale(s: float):
   _brush_scale = clampf(s, 0.0, 1.0)
   #_viewport_brush_sprite.scale = Vector2(s, s)


func get_brush_scale() -> float:
   return _viewport_bg_sprite.scale.x


func set_brush_opacity(opacity: float):
   _brush_opacity = clampf(opacity, 0.0, 1.0)


func get_brush_opacity() -> float:
   return _brush_opacity


func set_brush_texture(texture: Texture):
   _viewport_brush_sprite.texture = texture


func set_brush_shader(shader: Shader):
   if _brush_material.shader != shader:
      _brush_material.shader = shader


func set_brush_shader_param(p: String, v):
   assert(not _API_SHADER_PARAMS.has(p))
   _modified_shader_params[p] = true
   _brush_material.set_shader_parameter(p, v)


func clear_brush_shader_params():
   for key in _modified_shader_params:
      _brush_material.set_shader_parameter(key, null)
   _modified_shader_params.clear()


# If we want to be able to rotate the brush quad every frame,
# we must prepare a bigger viewport otherwise the quad will not fit inside
static func _get_size_fit_for_rotation(src_size: Vector2) -> Vector2i:
   var d = int(ceilf(src_size.length()))
   return Vector2i(d, d)


# You must call this from an `_input` function or similar.
func paint_input(center_pos: Vector2):
   var vp_size := _get_size_fit_for_rotation(Vector2(_brush_size, _brush_size))
   if _viewport.size != vp_size:
      # Do this lazily so the brush slider won't lag while adjusting it
      # TODO An "sliding_ended" handling might produce better user experience
      _viewport.size = vp_size
      _viewport_brush_sprite.position = _viewport.size / 2.0

   # Need to floor the position in case the brush has an odd size
   var brush_pos := (center_pos - _viewport.size * 0.5).round()
   _viewport.render_target_update_mode = SubViewport.UPDATE_ONCE
   _viewport.render_target_clear_mode = SubViewport.CLEAR_MODE_ONCE
   _viewport_bg_sprite.position = -brush_pos
   _brush_position = brush_pos
   _cmd_paint = true
   
   # We want this quad to have a specific size, regardless of the texture assigned to it
   _viewport_brush_sprite.scale = \
      _brush_scale * Vector2(_brush_size, _brush_size) \
      / Vector2(_viewport_brush_sprite.texture.get_size())

   # Using a Color because Godot doesn't understand vec4
   var rect := Color()
   rect.r = brush_pos.x / _texture.get_width()
   rect.g = brush_pos.y / _texture.get_height()
   rect.b = float(_viewport.size.x) / float(_texture.get_width())
   rect.a = float(_viewport.size.y) / float(_texture.get_height())
   # In order to make sure that u_brush_rect is never bigger than the brush:
   # 1. we ceil() the result of lower-left corner
   # 2. we floor() the result of upper-right corner
   # and then rederive width and height from the result
#  var half_brush:Vector2 = Vector2(_brush_size, _brush_size) / 2
#  var brush_LL := (center_pos - half_brush).ceil()
#  var brush_UR := (center_pos + half_brush).floor()
#  rect.r = brush_LL.x / _texture.get_width()
#  rect.g = brush_LL.y / _texture.get_height()
#  rect.b = (brush_UR.x - brush_LL.x) / _texture.get_width()
#  rect.a = (brush_UR.y - brush_LL.y) / _texture.get_height()
   _brush_material.set_shader_parameter(SHADER_PARAM_SRC_RECT, rect)
   _brush_material.set_shader_parameter(SHADER_PARAM_OPACITY, _brush_opacity)


# Don't commit until this is false
func is_operation_pending() -> bool:
   return _pending_paint_render or _cmd_paint


# Applies changes to the Image, and returns modified chunks for UndoRedo.
func commit() -> Dictionary:
   if is_operation_pending():
      _logger.error("Painter commit() was called while an operation is still pending")
   return _commit_modified_chunks()


func has_modified_chunks() -> bool:
   return len(_modified_chunks) > 0


func _process(delta: float):
   if _pending_paint_render:
      _pending_paint_render = false
   
      #print("Paint result at frame ", Engine.get_frames_drawn())
      var viewport_image := _viewport.get_texture().get_image()
      
      if _image.get_format() == Image.FORMAT_RF:
         # Reinterpret RGBA8 as RF. This assumes painting shaders encode the output properly.
         assert(viewport_image.get_format() == Image.FORMAT_RGBA8)
         viewport_image = Image.create_from_data(
            viewport_image.get_width(), viewport_image.get_height(), false, Image.FORMAT_RF, 
            viewport_image.get_data())
      else:
         viewport_image.convert(_image.get_format())
      
      var brush_pos := _last_brush_position
      
      var dst_x : int = clamp(brush_pos.x, 0, _texture.get_width())
      var dst_y : int = clamp(brush_pos.y, 0, _texture.get_height())
      
      var src_x : int = maxf(-brush_pos.x, 0)
      var src_y : int = maxf(-brush_pos.y, 0)
      var src_w : int = minf(maxf(_viewport.size.x - src_x, 0), _texture.get_width() - dst_x)
      var src_h : int = minf(maxf(_viewport.size.y - src_y, 0), _texture.get_height() - dst_y)
      
      if src_w != 0 and src_h != 0:
         _mark_modified_chunks(dst_x, dst_y, src_w, src_h)
         HT_Util.update_texture_partial(_texture, viewport_image,
            Rect2i(src_x, src_y, src_w, src_h), Vector2i(dst_x, dst_y))
         texture_region_changed.emit(Rect2(dst_x, dst_y, src_w, src_h))
   
   # Input is handled just before process, so we still have to wait till next frame
   if _cmd_paint:
      _pending_paint_render = true
      _last_brush_position = _brush_position
      # Consume input
      _cmd_paint = false


func _mark_modified_chunks(bx: int, by: int, bw: int, bh: int):
   var cs := UNDO_CHUNK_SIZE
   
   var cmin_x := bx / cs
   var cmin_y := by / cs
   var cmax_x := (bx + bw - 1) / cs + 1
   var cmax_y := (by + bh - 1) / cs + 1
   
   for cy in range(cmin_y, cmax_y):
      for cx in range(cmin_x, cmax_x):
         #print("Marking chunk ", Vector2(cx, cy))
         _modified_chunks[Vector2(cx, cy)] = true


func _commit_modified_chunks() -> Dictionary:
   var time_before := Time.get_ticks_msec()
   
   var cs := UNDO_CHUNK_SIZE
   var chunks_positions := []
   var chunks_initial_data := []
   var chunks_final_data := []

   #_logger.debug("About to commit ", len(_modified_chunks), " chunks")
   
   # TODO get_data_partial() would be nice...
   var final_image := _texture.get_image()
   for cpos in _modified_chunks:
      var cx : int = cpos.x
      var cy : int = cpos.y
      
      var x := cx * cs
      var y := cy * cs
      var w : int = mini(cs, _image.get_width() - x)
      var h : int = mini(cs, _image.get_height() - y)
      
      var rect := Rect2i(x, y, w, h)
      var initial_data := _image.get_region(rect)
      var final_data := final_image.get_region(rect)
      
      chunks_positions.append(cpos)
      chunks_initial_data.append(initial_data)
      chunks_final_data.append(final_data)
      #_image_equals(initial_data, final_data)
      
      # TODO We could also just replace the image with `final_image`...
      # TODO Use `final_data` instead?
      _image.blit_rect(final_image, rect, rect.position)
   
   _modified_chunks.clear()
   
   var time_spent := Time.get_ticks_msec() - time_before
   _logger.debug("Spent {0} ms to commit paint operation".format([time_spent]))
   
   return {
      "chunk_positions": chunks_positions,
      "chunk_initial_datas": chunks_initial_data,
      "chunk_final_datas": chunks_final_data
   }


# DEBUG
#func _input(event):
#  if event is InputEventKey:
#     if event.pressed:
#        if event.control and event.scancode == KEY_SPACE:
#           print("Saving painter viewport ", name)
#           var im = _viewport.get_texture().get_data()
#           im.convert(Image.FORMAT_RGBA8)
#           im.save_png(str("test_painter_viewport_", name, ".png"))


#static func _image_equals(im_a: Image, im_b: Image) -> bool:
#  if im_a.get_size() != im_b.get_size():
#     print("Diff size: ", im_a.get_size, ", ", im_b.get_size())
#     return false
#  if im_a.get_format() != im_b.get_format():
#     print("Diff format: ", im_a.get_format(), ", ", im_b.get_format())
#     return false
#  im_a.lock()
#  im_b.lock()
#  for y in im_a.get_height():
#     for x in im_a.get_width():
#        var ca = im_a.get_pixel(x, y)
#        var cb = im_b.get_pixel(x, y)
#        if ca != cb:
#           print("Diff pixel ", x, ", ", y)
#           return false
#  im_a.unlock()
#  im_b.unlock()
#  print("SAME")
#  return true