Beginning of a custom TCastleMeshCollider descendant that can read information from PhysicsEditor PLIST file

castlecolliderfromphysicseditor.pas

{ Sketch of a custom TCastleMeshCollider descendant,
  that can read the information
  from https://github.com/CodeAndWeb/PhysicsEditor-Loaders/ .

  Consider it public domain, do with it whatever you want,
  I hope it will help any contributor interested in implementing
  https://github.com/CodeAndWeb/PhysicsEditor-Loaders/issues/17 . }
unit CastleColliderFromPhysicsEditor;

interface

uses CastleTransform, CastleScene;

type
  TCastleColliderFromPhysicsEditor = class(TCastleMeshCollider)
  strict private
    FUrl: String;
    FInternalMesh: TCastleScene;
    procedure SetUrl(const Value: string);
  published
    property Url: string read FUrl write SetUrl;
  end;

implementation

uses Dom, SysUtils,
  CastleXmlUtils, X3DNodes, CastleVectors;

procedure TCastleColliderFromPhysicsEditor.SetUrl(const Value: string);
var
  Doc: TXmlDocument;
  Coord: TCoordinateNode;
  IndexedTriangleSet: TIndexedTriangleSetNode;
  Shape: TShapeNode;
  RootNode: TX3DRootNode;
begin
  if FUrl <> Value then
  begin
    FUrl := Value;

    { Recreate FInternalMesh and assign it to ancesotr's Mesh property }
    Doc := UrlReadXml(Value);
    try
      { TODO: Parse information from Doc.
        For a sample how to read data from PLIST (a special case of XML)
        you can take a look at X3DLoadInternalCocos2d unit in CGE,
        see src/scene/load/x3dloadinternalcocos2d.pas in CGE sources.

        For now, code below just creates a simple triangle
        from 3 3D points. }

      FreeAndNil(FInternalMesh);

      { Create a set of nodes and TCastleScene that describes the collider
        shape. Based on
        https://castle-engine.io/viewport_and_scenes_from_code#_building_a_mesh_using_code .

        Note that the FInternalMesh will be never really visible,
        so we don't care about assigning any fancy material.
      }

      Coord := TCoordinateNode.Create;
      Coord.SetPoint([
        Vector3(-15.205387, -66.775894, -0.092525),
        Vector3(9.317978, -66.775894, -0.092525),
        Vector3(-15.205387, -68.674622, -0.092525)
      ]);

      IndexedTriangleSet := TIndexedTriangleSetNode.Create;
      IndexedTriangleSet.Coord := Coord;
      IndexedTriangleSet.SetIndex([0, 1, 2]);

      Shape := TShapeNode.Create;
      Shape.Geometry := IndexedTriangleSet;

      RootNode := TX3DRootNode.Create;
      RootNode.AddChildren(Shape);

      FInternalMesh := TCastleScene.Create(Self);
      FInternalMesh.Load(RootNode, true);

      Mesh := FInternalMesh;
    finally FreeAndNil(Doc) end;
  end;
end;

end.