Title: MNCadBuilder - RapidCAD with Delphi (OpenGL) (part II)
Question: Delphi and 3D CAD development - drawing user defines shapes
Answer:
1. Please make sure you have read article "MNCadBuilder - RapidCAD with Delphi" to avoid installation or configuration problems.
2. Let's take a look at defining "user defined" shapes
-----------------------------------------------------
Create a new project.
Please make sure, that the root path of your MNCB installation folder is in the search path.
Start "Project" - "Options" - select folder "Directories/Conditionals" and add the MNCB folder to the "Search path" settings.
Now we drag and drop a TMNOglCanvas component on to the form.
TMNOglCanvas is the central component for drawing and render output.
When assigning a Window control to the property WinControl, an "OpenGL render context" is created based on the Window Handle of the Window control.
So, let us assign the Form (Form1) to the WinControl.
We also change the BackgroundColor of the TMNOglCanvas to get a more friendly
background color (maybe clCream).
Now we define a new type of Entity:
TYPE
TMyShape = class (TMNEntity)
private
protected
procedure Draw; override;
public
end;
Let's fill the Draw method with some life:
procedure TMyShape.Draw;
begin
// Draw a box of length=3 at position TMyShape.Base
MNDevice.DrawBox(NewPt (3,3,3));
// push the current ModelMatrix
MNDevice.PushMatrix;
// modify the ModelMatrix by a translation
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(1,1,-1)));
// draw some primitive
MNDevice.DrawBox(NewPt (1,1,1));
// and pop the pushed Modelmatrix
MNDevice.PopMatrix;
MNDevice.PushMatrix;
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(-1,1,1)));
MNDevice.DrawBox(NewPt (1,1,1));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(1,1,3)));
MNDevice.DrawBox(NewPt (1,1,1));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(3,1,1)));
MNDevice.DrawBox(NewPt (1,1,1));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(1,3,1)));
MNDevice.DrawBox(NewPt (1,1,1));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
MNDevice.MultMatrix(TranslationToMatrix3D (NewPt(1,-1,1)));
MNDevice.DrawBox(NewPt (1,1,1));
MNDevice.PopMatrix;
end;
... or with variables:
procedure TMyShape.Draw;
const
ssize = 1.5;
lsize = 4;
var
trans : TXYZ;
begin
// Draw a box of length=lsize at position Base
MNDevice.DrawBox(NewPt (lsize,lsize,lsize));
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize/2-ssize/2,-ssize);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(-ssize,lsize/2-ssize/2,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize/2-ssize/2,lsize);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize,lsize/2-ssize/2,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,-ssize,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
end;
We create the shape in the Form's OnShow method ...
procedure TForm1.FormShow(Sender: TObject);
begin
// create a shape of type TMyShape
MyShape := TMyShape.Create (NIL);
// tell the Device to draw MyShape
MNOglCanvas1._Entity := MyShape;
end;
.. and we dispose the object in the Form's Close method:
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
MyShape.Free;
end;
When we set the MNOglCanvas property Navigate to TRUE, we can change the view of the MNOglCanvas at runtime (means changing the projection matrix of the canvas).
When start the project, we see the "user defined" shape. Because of Navigate is TRUE, we can change the view by pressing the left mouse button and moving the mouse. When you additionally press the [Ctrl] key you can translate the view in X and Y.
If you want a perspective view, you can change the MNOglCanvas property FieldOfView to a value 0 (e.g. 20 degree). After restarting the project you see the object in a perspective view. And now we can also translate the view in Z axis by pressing the [Shift] key, left mouse button down and moving the mouse in Y+/- direction.
This was an introduction of "user defined shapes" with the MNCadBuilder.
Here you will find the source.
Leopold Minikus
DeveloCAD.com
This is the source of the pas file:
unit _Beginner2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs,
_MNDevice, _MNObjects3D, _MNPlatform, _MNOglCanvas, _MNMath, _MNXYZ;
type
TForm1 = class(TForm)
MNOglCanvas1: TMNOglCanvas;
procedure FormShow(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private-Deklarationen }
public
{ Public-Deklarationen }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
TYPE
TMyShape = class (TMNEntity)
private
protected
procedure Draw; override;
public
end;
VAR
MyShape : TMyShape;
procedure TForm1.FormShow(Sender: TObject);
begin
// create a shape of type TMyShape
MyShape := TMyShape.Create (NIL);
// tell the Device to draw MyShape
MNOglCanvas1._Entity := MyShape;
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
MyShape.Free;
end;
{ TMyShape }
procedure TMyShape.Draw;
const
ssize = 1.5;
lsize = 4;
var
trans : TXYZ;
begin
// Draw a box of length=lsize at position Base
MNDevice.DrawBox(NewPt (lsize,lsize,lsize));
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize/2-ssize/2,-ssize);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(-ssize,lsize/2-ssize/2,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize/2-ssize/2,lsize);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize,lsize/2-ssize/2,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,lsize,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
MNDevice.PushMatrix;
trans := NewPt(lsize/2-ssize/2,-ssize,lsize/2-ssize/2);
MNDevice.MultMatrix(TranslationToMatrix3D (trans));
MNDevice.DrawBox(NewPt (ssize,ssize,ssize));
MNDevice.PopMatrix;
end;
end.
This is the source of the dfm file:
object Form1: TForm1
Left = 350
Top = 335
Width = 736
Height = 464
Caption = 'Form1'
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -13
Font.Name = 'MS Sans Serif'
Font.Style = []
OldCreateOrder = False
OnClose = FormClose
OnShow = FormShow
PixelsPerInch = 120
TextHeight = 16
object MNOglCanvas1: TMNOglCanvas
MNName = 'MNOglCanvas1'
BackgroundColor = 15793151
Culling = True
Cursor = CR_Cross
DefaultLight = True
DefaultPixelsPerUnit = 30.000000000000000000
FieldOfView = 20.000000000000000000
FontName = 'Modern'
FontSize = 40
Lightning = True
CanFocus = True
WinControl = Owner
ZoomFactor = 1.000000000000000000
DrawFocusRect = False
Navigate = True
EyeLight = True
_ProjectionBase.BaseX.x = 1.000000000000000000
_ProjectionBase.BaseY.y = 1.000000000000000000
_ProjectionBase.BaseZ.z = 1.000000000000000000
PixelsPerUnit = 30.000000000000000000
Left = 64
Top = 56
end
end