SCENE P1X

Architecture

BAD LOOKING CUBE DEMOTOOL PIPELINE
Blender + Plugin	CSV Screenplay Interpreter	OpenGL Renderer and Time-based Animation
Python	Delphi 7 Pascal	Delphi 7 Pascal, OpenGL (1.x)
Designing models and vertex painting Exporting OBJ's Set dressing level Animating Camera movement Setting basic scene properties (sky, fog) Exporting scene group and animations to CSV	Reading CSV Loading models Setting up scene Filling objects with animations from CSV	Window rendering 3D Scene rendering Translating, scaling, rotating, and cloning objects Linear and smooth interpolation (time-based) Smooth and flat shading Camera FOV Fog MIDI playback

Useful Code Snippets

As I was writing new engine from scratch I collected a bunch of useful tricks. I'm sharing it for everyone!

Enabling V-SYNC (GL)

type
  TWglSwapIntervalEXT = procedure(interval: GLInt); stdcall;

var
  wglSwapIntervalEXT: TWglSwapIntervalEXT;

procedure InitVSync;
begin
  if not Assigned(wglSwapIntervalEXT) then
  begin
    wglSwapIntervalEXT := wglGetProcAddress('wglSwapIntervalEXT');
    if not Assigned(wglSwapIntervalEXT) then Exit;
  end;
  wglSwapIntervalEXT(1);
end;

Fixing Window Blinking (Redraing)

Rendering OpenGL content in a window is in conflict with internal redrawing of a window. To fix this you need to disable this by overwiting internal procedure.

TFormDemo = class(TForm)
private
  procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
      
procedure TFormDemo.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
  Message.Result := 1;
end;

Lerping

function Lerp(A, B, T: glFloat; Linear: Boolean): glFloat;
var
  TD: Double;
begin
  if Linear then
  begin
    Result := A + (B - A) * T;
  end
  else
  begin
    TD := (1-Cos(T*PI))/2;
    Result := A*(1-TD)+B*TD;
  end;
end;

Accessing Relative Files

At the creation of a window set current path.

SetCurrentDir(ExtractFilePath(Application.ExeName));

Then access file in current (binary) directory.

var
  CSVFile: TextFile;
  Line: String;
  Fields: TStringList;

begin
  AssignFile(CSVFile, 'screenplay.csv');
  Reset(CSVFile);
  Fields := TStringList.Create;
  Fields.Delimiter := ',';
  try
    while not Eof(CSVFile) do
    begin
      ReadLn(CSVFile, Line);
      Fields.DelimitedText := Line;
      ...
    end
  finally
    Fields.Free;
    CloseFile(CSVFile);
  end;
end;

Frame Time Calculation

var
  LastFrameTime, CurrentTime, FrameTime: TDateTime;

// render loop
begin
  CurrentTime := Now;
  FrameTime := MilliSecondsBetween(CurrentTime, LastFrameTime);
  LastFrameTime := CurrentTime;

  ... render frame ...
  
  LabelFrameTime.Caption := Format('%.2fms', [FrameTime]);
end;

Loading Models from Resourece File

Create resource definition file.

models.rc

Inside write resource name and path to actual file. One file per line.

SM_Skybox RCDATA Models/skybox.obj
SM_Terrain RCDATA Models/terrain.obj
SM_Model01 RCDATA Models/model_01.obj
...

Compile resource package. This command will create models.RES package file.

brcc32 models.rc

Add resource files (package + definitions).

implementation
  {$R 'models.RES' 'models.rc'}

Reading data from resource.

function ReadOBJFileFromResource(const ResourceName: string): TModel;
var
  ResStream: TResourceStream;
  FileLines: TStringList;
  i,f: Integer;
  Line: string;
  Model: TModel;
begin
  ResStream := TResourceStream.Create(HInstance, ResourceName, RT_RCDATA);
  FileLines := TStringList.Create;

  try
    FileLines.LoadFromStream(ResStream);

    for i := 0 to FileLines.Count - 1 do
    begin
      Line := Trim(FileLines[i]);
     
      ... read data for model Model ...

    end;
  finally
    FileLines.Free;
  end;
  
  Result := Model;
end;

Model := ReadOBJFileFromResource('SM_Model01');

Calculate Position Between Points for Lerp

Based on current demo time calculate value for lerp between two points in timeline. This makes time-based animation easy.

function CalcPos(A,B,T: glFloat): glFloat;
begin
  Result := 0;
  if A<>B then
  begin
    Result := (T-A)/(B-A);
  end
  else
  begin
    Result := Max(0.0,Min(Result,1.0));
  end;
end;

Pos := CalcPos(Timeline[Prev].Timestamp, Timeline[Next].Timestamp, DemoTime);
Position.X := Lerp(Timeline[Prev].Params[_X], Timeline[Next].Params[_X], Pos);

Gallery

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Links

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