Updated drawing method to use proper gl methods and added TView to handle OpenGL initialization

ProductionGraph.lpi

@@ -44,12 +44,16 @@
         <HasResources Value="True"/>
         <ResourceBaseClass Value="Form"/>
       </Unit>
+      <Unit>
+        <Filename Value="UView.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
       <Unit>
         <Filename Value="UDraw.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit>
       <Unit>
-        <Filename Value="utils\UColor3f.pas"/>
+        <Filename Value="utils\UGLTypes.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit>
     </Units>
@@ -81,6 +85,7 @@
     </CodeGeneration>
     <Linking>
       <Debugging>
+        <DebugInfoType Value="dsDwarf2"/>
         <UseHeaptrc Value="True"/>
       </Debugging>
       <Options>

ProductionGraph.lpr

@@ -10,7 +10,7 @@ uses
   athreads,
   {$ENDIF}
   Interfaces, // this includes the LCL widgetset
-  Forms, lazopenglcontext, UMainForm, UDraw, UColor3f;
+  Forms, lazopenglcontext, UMainForm, UView, UDraw, UGLTypes;
 
 {$R *.res}
 

UDraw.pas

@@ -5,7 +5,12 @@ unit UDraw;
 interface
 
 uses
-  Classes, SysUtils, gl, UColor3f;
+  Classes, SysUtils, gl, UGLTypes;
+
+const
+  // The number of sections per corner must be at least 1.
+  CCornerSectionCount = 4;
+  CCornerSectionAngle = Pi / (2 * CCornerSectionCount);
 
 type
 
@@ -13,78 +18,80 @@ type
 
   TDraw = class
   public
-    class procedure Clear; static;
-    class procedure AddBox(AWidth, AHeight, ACornerSize: Single); static;
-    class procedure AddRoundedCornerVertices(AHalfWidth, AHalfHeight,
-      ACornerSize: Single; AIndex: Integer); static;
+    class constructor Create;
+    class procedure AddRoundBox(ACenterX, ACenterY, AWidth, AHeight,
+      ACornerSize: Single); static;
+  private
+    FCornerSectionVertices: array[0..CCornerSectionCount + 1] of TVertex3f; static;
+    class procedure MakeVertexList; static;
   end;
 
-const
-  CBackgroundColor: TColor3f = (R: 0.27; G: 0.53; B: 0.71);
-  CRoundedCornerVertexCount = 4;
-  CRoundedCornerVertexAngle = Pi / (2 * CRoundedCornerVertexCount + 2);
-
 implementation
 
 { TDraw }
 
-class procedure TDraw.Clear;
+class constructor TDraw.Create;
 begin
-  glClearColor(CBackgroundColor.R, CBackgroundColor.G, CBackgroundColor.B, 0);
-  glClear(GL_COLOR_BUFFER_BIT);
+  MakeVertexList;
 end;
 
-class procedure TDraw.AddBox(AWidth, AHeight, ACornerSize: Single);
+class procedure TDraw.AddRoundBox(ACenterX, ACenterY, AWidth, AHeight,
+  ACornerSize: Single);
 var
-  i: Integer;
-  halfWidth, halfHeight: Single;
+  i, flip: Integer;
 begin
-  halfWidth := 0.5 * AWidth;
-  halfHeight := 0.5 * AHeight;
-
-  glBegin(GL_TRIANGLE_FAN);
-    glColor3f(1, 1, 1);
-    if ACornerSize > TSingleHelper.Epsilon then
+  glPushMatrix;
+    // Draws a cross from two quads: the panel without the corners.
+    glTranslatef(ACenterX, ACenterY, 0);
+    glPushMatrix;
+      glTranslatef(-0.5 * AWidth, -0.5 * AHeight, 0);
+      glBegin(GL_QUADS);
+        glColor3f(1, 1, 1);
+        glVertex2f(AWidth - ACornerSize, AHeight);
+        glVertex2f(ACornerSize, AHeight);
+        glVertex2f(ACornerSize, 0);
+        glVertex2f(AWidth - ACornerSize, 0);
+        glVertex2f(AWidth, AHeight - ACornerSize);
+        glVertex2f(0, AHeight - ACornerSize);
+        glVertex2f(0, ACornerSize);
+        glVertex2f(AWidth, ACornerSize);
+      glEnd;
+    glPopMatrix;
+
+    // Draws the four corners by mirroring one fan of triangles. Its vertex
+    // coordinates are precalculated in 'FCornerSectionVertices'.
+    for i := 0 to 3 do
     begin
-      // With round corners, the fan's origin is the center of the panel.
-      glVertex2f(0.0, 0.0);
-      for i := 0 to 4 do
-        AddRoundedCornerVertices(halfWidth, halfHeight, ACornerSize, i);
-    end
-    else begin
-      // Without round corners, the panel is just two triangles.
-      glVertex2f(halfWidth, halfHeight);
-      glVertex2f(-halfWidth, halfHeight);
-      glVertex2f(-halfWidth, -halfHeight);
-      glVertex2f(halfWidth, -halfHeight);
+      glPushMatrix;
+        glTranslatef(0.5 * AWidth - ACornerSize, 0.5 * AHeight - ACornerSize, 0);
+        glScalef(ACornerSize, ACornerSize, 1);
+        glEnableClientState(GL_VERTEX_ARRAY);
+        glVertexPointer(3, GL_FLOAT, 0, @FCornerSectionVertices[0]);
+        glDrawArrays(GL_TRIANGLE_FAN, 0, Length(FCornerSectionVertices));
+        glDisableClientState(GL_VERTEX_ARRAY);
+      glPopMatrix;
+      flip := 2 * (i and 1);
+      glScalef(flip - 1, 1 - flip, 1);
     end;
-  glEnd;
+  glPopMatrix;
 end;
 
-class procedure TDraw.AddRoundedCornerVertices(AHalfWidth, AHalfHeight, ACornerSize:
-  Single; AIndex: Integer);
+class procedure TDraw.MakeVertexList;
 var
-  i, signX, signY, cornerSign: Integer;
-  borderX, borderY, phi: Single;
+  i, last: Integer;
 begin
-  signX := 1 - (AIndex + 1) and 2;
-  borderX := signX * AHalfWidth;
-  signY := 1 - AIndex and 2;
-  borderY := signY * AHalfHeight;
-  cornerSign := AIndex and 1;
-
-  glVertex2f(borderX - signX * cornerSign * ACornerSize, borderY + signY * (cornerSign - 1) * ACornerSize);
-
-  // For the last call only the first vertex is added to close the loop.
-  if AIndex >= 4 then
-    Exit;
-
-  for i := 1 to CRoundedCornerVertexCount do
+  FCornerSectionVertices[0].X := 0;
+  FCornerSectionVertices[0].Y := 0;
+  FCornerSectionVertices[1].X := 1;
+  FCornerSectionVertices[1].Y := 0;
+  last := Length(FCornerSectionVertices) - 1;
+  for i := 2 to last - 1 do
   begin
-    phi := (i + AIndex * (CRoundedCornerVertexCount + 1)) * CRoundedCornerVertexAngle;
-    glVertex2f(borderX + (Cos(phi) - signX) * ACornerSize, borderY + (Sin(phi) - signY) * ACornerSize);
+    FCornerSectionVertices[i].X := Cos(CCornerSectionAngle * (i - 1));
+    FCornerSectionVertices[i].Y := Sin(CCornerSectionAngle * (i - 1));
   end;
-  glVertex2f(borderX + signX * (cornerSign - 1) * ACornerSize, borderY - signY * cornerSign * ACornerSize);
+  FCornerSectionVertices[last].X := 0;
+  FCornerSectionVertices[last].Y := 1;
 end;
 
 end.

UMainForm.lfm

@@ -6,6 +6,8 @@ object MainForm: TMainForm
   Caption = 'MainForm'
   ClientHeight = 480
   ClientWidth = 640
+  OnCreate = FormCreate
+  OnDestroy = FormDestroy
   LCLVersion = '2.2.4.0'
   object OpenGLControl: TOpenGLControl
     Left = 0
@@ -13,6 +15,7 @@ object MainForm: TMainForm
     Top = 0
     Width = 640
     Align = alClient
+    OnClick = OpenGLControlClick
     OnPaint = OpenGLControlPaint
   end
 end

UMainForm.pas

@@ -6,7 +6,7 @@ interface
 
 uses
   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, OpenGLContext, gl,
-  UDraw;
+  UView, UDraw;
 
 type
 
@@ -14,17 +14,22 @@ type
 
   TMainForm = class(TForm)
     OpenGLControl: TOpenGLControl;
+    procedure FormCreate(Sender: TObject);
+    procedure FormDestroy(Sender: TObject);
+    procedure OpenGLControlClick(Sender: TObject);
     procedure OpenGLControlPaint(Sender: TObject);
   private
-
+    FView: TView;
   public
 
   end;
 
 const
-  CWidth = 0.4;
-  CHeight = 0.5;
-  CCornerSize = 0.1;
+  CCenterX = 250;
+  CCenterY = 200;
+  CWidth = 200;
+  CHeight = 300;
+  CCornerSize = 30;
 
 var
   MainForm: TMainForm;
@@ -35,11 +40,33 @@ implementation
 
 { TMainForm }
 
+procedure TMainForm.FormCreate(Sender: TObject);
+begin
+  FView := TView.Create(OpenGLControl);
+end;
+
+procedure TMainForm.FormDestroy(Sender: TObject);
+begin
+  FView.Free;
+end;
+
+procedure TMainForm.OpenGLControlClick(Sender: TObject);
+begin
+  // TODO: This is just a workaround until we find a better place for the init.
+  FView.OpenGLInit(True);
+  OpenGLControl.Repaint;
+end;
+
 procedure TMainForm.OpenGLControlPaint(Sender: TObject);
 begin
-  TDraw.Clear;
+  // Prepares drawing.
+  FView.Clear;
   glLoadIdentity;
-  TDraw.AddBox(CWidth, CHeight, CCornerSize);
+
+  // Draws everything.
+  TDraw.AddRoundBox(CCenterX, CCenterY, CWidth, CHeight, CCornerSize);
+
+  // Finishes drawing.
   OpenGLControl.SwapBuffers;
 end;
 

UView.pas

@@ -0,0 +1,59 @@
+unit UView;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, OpenGLContext, gl, glu, UGLTypes;
+
+type
+
+  { TView }
+
+  TView = class
+  public
+    constructor Create(AOpenGLControl: TOpenGLControl);
+    procedure OpenGLInit(AResetModelView: Boolean);
+    procedure Clear;
+  private
+    FOpenGLControl: TOpenGLControl;
+  end;
+
+const
+  CBackgroundColor: TColor3f = (R: 0.27; G: 0.53; B: 0.71);
+
+implementation
+
+{ TView }
+
+constructor TView.Create(AOpenGLControl: TOpenGLControl);
+begin
+  FOpenGLControl := AOpenGLControl;
+  FScale := 1;
+end;
+
+// TODO: Do we need 'AResetModelView'?
+procedure TView.OpenGLInit(AResetModelView: Boolean);
+begin
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity;
+  glViewport(0, 0, FOpenGLControl.Width, FOpenGLControl.Height);
+  gluOrtho2D(0, FOpenGLControl.Width, 0, FOpenGLControl.Height);
+  glMatrixMode(GL_MODELVIEW);
+  if AResetModelView then
+    glLoadIdentity;
+
+  glDisable(GL_DEPTH_TEST);
+  glEnable(GL_BLEND);
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+end;
+
+procedure TView.Clear;
+begin
+  glClearColor(CBackgroundColor.R, CBackgroundColor.G, CBackgroundColor.B, 0);
+  glClear(GL_COLOR_BUFFER_BIT);
+end;
+
+end.
+

utils/UGLTypes.pas

@@ -1,4 +1,4 @@
-unit UColor3f;
+unit UGLTypes;
 
 {$mode ObjFPC}{$H+}
 
@@ -8,6 +8,10 @@ uses
   Classes, SysUtils;
 
 type
+  TVertex3f = record
+    X, Y, Z: Single;
+  end;
+
   TColor3f = record
     R, G, B: Single;
   end;