Delphi自定义动画 - 碰撞检测

Question

我正在使用自定义绘图/ 2D动画,我正在试图弄清楚如何检测移动物体何时与地图中的墙碰撞.用户在键盘上按住箭头键移动对象,地图存储为点的数组结构.地图中的墙壁可以成角度,但没有弯曲的墙壁.

FMap: TMap;在下面的代码中使用地图结构(),在DoMove属性中,如何检测对象是否与地图中的任何墙碰撞并阻止其移动？在DoMove,我需要阅读FMap(参考DrawMap看看如何FMap工作)并以某种方式确定对象是否接近任何墙并停止它.

我可以做一个双X/Y循环迭代每个映射的每个部分中每两个点之间的每个可能的像素,但我已经知道这将是很重的,考虑到只要对象移动就会快速调用此过程.

我想到了在物体移动方向上读取像素颜色,如果有任何黑色(来自地图线),请将其视为墙.但最终会有更多自定义绘制背景,因此读取像素颜色将无法正常工作.

uMain.pas

unit uMain;

interface

uses
  Winapi.Windows, Winapi.Messages,
  System.SysUtils, System.Variants, System.Classes,
  Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;

const
  //Window client size
  MAP_WIDTH = 500;
  MAP_HEIGHT = 500;

type
  TKeyStates = Array[0..255] of Bool;
  TPoints = Array of TPoint;
  TMap = Array of TPoints;

  TForm1 = class(TForm)
    Tmr: TTimer;
    procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
    procedure FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
    procedure TmrTimer(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormPaint(Sender: TObject);
  private
    FBMain: TBitmap;    //Main rendering image
    FBMap: TBitmap;     //Map image
    FBObj: TBitmap;     //Object image
    FKeys: TKeyStates;  //Keyboard states
    FPos: TPoint;       //Current object position
    FMap: TMap;         //Map line structure
    procedure Render;
    procedure DrawObj;
    procedure DoMove;
    procedure DrawMap;
    procedure LoadMap;
  public

  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  Math, StrUtils;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FBMain:= TBitmap.Create;
  FBMap:= TBitmap.Create;
  FBObj:= TBitmap.Create;
  ClientWidth:= MAP_WIDTH;
  ClientHeight:= MAP_HEIGHT;
  FBMain.Width:= MAP_WIDTH;
  FBMain.Height:= MAP_HEIGHT;
  FBMap.Width:= MAP_WIDTH;
  FBMap.Height:= MAP_HEIGHT;
  FBObj.Width:= MAP_WIDTH;
  FBObj.Height:= MAP_HEIGHT;
  FBObj.TransparentColor:= clWhite;
  FBObj.Transparent:= True;
  FPos:= Point(150, 150);
  LoadMap;    //Load map lines into array structure
  DrawMap;    //Draw map lines to map image only once
  Tmr.Enabled:= True;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  Tmr.Enabled:= False;
  FBMain.Free;
  FBMap.Free;
  FBObj.Free;
end;

procedure TForm1.LoadMap;
begin
  SetLength(FMap, 1);     //Just one object on map
  //Triangle
  SetLength(FMap[0], 4);  //4 points total
  FMap[0][0]:= Point(250, 100);
  FMap[0][1]:= Point(250, 400);
  FMap[0][2]:= Point(100, 400);
  FMap[0][3]:= Point(250, 100);
end;

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  FKeys[Key]:= True;
end;

procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
  FKeys[Key]:= False;
end;

procedure TForm1.FormPaint(Sender: TObject);
begin
  Canvas.Draw(0, 0, FBMain);  //Just draw rendered image to form
end;

procedure TForm1.DoMove;
const
  SPD = 3;  //Speed (pixels per movement)
var
  X, Y: Integer;
  P: TPoints;
begin
  //How to keep object from passing through map walls?
  if FKeys[VK_LEFT] then begin
    //Check if there's a wall on the left

    FPos.X:= FPos.X - SPD;
  end;
  if FKeys[VK_RIGHT] then begin
    //Check if there's a wall on the right

    FPos.X:= FPos.X + SPD;
  end;
  if FKeys[VK_UP] then begin
    //Check if there's a wall on the top

    FPos.Y:= FPos.Y - SPD;
  end;
  if FKeys[VK_DOWN] then begin
    //Check if there's a wall on the bottom

    FPos.Y:= FPos.Y + SPD;
  end;
end;

procedure TForm1.DrawMap;
var
  C: TCanvas;
  X, Y: Integer;
  P: TPoints;
begin
  C:= FBMap.Canvas;
  //Clear image first
  C.Brush.Style:= bsSolid;
  C.Pen.Style:= psClear;
  C.Brush.Color:= clWhite;
  C.FillRect(C.ClipRect);
  //Draw map walls
  C.Brush.Style:= bsClear;
  C.Pen.Style:= psSolid;
  C.Pen.Width:= 2;
  C.Pen.Color:= clBlack;
  for X := 0 to Length(FMap) - 1 do begin
    P:= FMap[X];    //One single map object
    for Y := 0 to Length(P) - 1 do begin
      if Y = 0 then //First iteration only
        C.MoveTo(P[Y].X, P[Y].Y)
      else          //All remaining iterations
        C.LineTo(P[Y].X, P[Y].Y);
    end;
  end;
end;

procedure TForm1.DrawObj;
var
  C: TCanvas;
  R: TRect;
begin
  C:= FBObj.Canvas;
  //Clear image first
  C.Brush.Style:= bsSolid;
  C.Pen.Style:= psClear;
  C.Brush.Color:= clWhite;
  C.FillRect(C.ClipRect);
  //Draw object in current position
  C.Brush.Style:= bsClear;
  C.Pen.Style:= psSolid;
  C.Pen.Width:= 2;
  C.Pen.Color:= clRed;
  R.Left:= FPos.X - 10;
  R.Right:= FPos.X + 10;
  R.Top:= FPos.Y - 10;
  R.Bottom:= FPos.Y + 10;
  C.Ellipse(R);
end;

procedure TForm1.Render;
begin
  //Combine map and object images into main image
  FBMain.Canvas.Draw(0, 0, FBMap);
  FBMain.Canvas.Draw(0, 0, FBObj);
  Invalidate; //Repaint
end;

procedure TForm1.TmrTimer(Sender: TObject);
begin
  DoMove;   //Control movement of object
  DrawObj;  //Draw object
  Render;
end;

end.

uMain.dfm

object Form1: TForm1
  Left = 315
  Top = 113
  BorderIcons = [biSystemMenu]
  BorderStyle = bsSingle
  Caption = 'Form1'
  ClientHeight = 104
  ClientWidth = 207
  Color = clBtnFace
  DoubleBuffered = True
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poScreenCenter
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  OnKeyDown = FormKeyDown
  OnKeyUp = FormKeyUp
  OnPaint = FormPaint
  PixelsPerInch = 96
  TextHeight = 13
  object Tmr: TTimer
    Enabled = False
    Interval = 50
    OnTimer = TmrTimer
    Left = 24
    Top = 8
  end
end

PS - 这段代码只是我完整项目的一个剥离和dummied版本,用于演示工作原理.

---

编辑

我刚刚意识到一个重要的因素:现在,我只实现了一个移动物体.但是,也会有多个移动物体.因此,碰撞可能发生在地图墙或另一个对象(我将列表中的每个对象).完整的项目仍然非常原始,就像这个样本一样,但代码要多于这个问题.

Answer 1

我已经在问题本身中回答了我自己的问题了一半。我想到的一件事是沿着运动方向读取图像的像素，并检查那里是否有一条线。我现在意识到我可以在FBMap地图图层下有一个额外的图层作为背景，并保留地图图层不变，只绘制可碰撞的墙壁。

移动时，扫描该特定图层上移动方向的像素，而不是整个图像。由于我已经在那里放置了一个预先绘制的图层，因此我可以读取它而不是主图像。根据移动的速度，我只需要向前看这么多像素（至少比移动的像素数多几个像素）。

另外，如果图像的背景有代表墙壁的图片而不是直线，则根本不需要绘制该图层。该层可以明确地用于在移动之前扫描几个像素以查找碰撞区域。事实上，由于我还需要识别与其他移动物体的碰撞，因此我也可以在这里绘制所有物体（黑/白）。

画布上的几次像素迭代（例如 20 个）与地图线中的大量迭代（例如 2000 个）相比根本不算什么。