Help (OpenGL-FPC) with the graphic of the view of two polygons in 3D
lazarus / 70-OpenGL

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carlejt · 2011-06-23 04:56

Hello

My problem is to represent the view of two polygons in 3D, using Free
Pascal and OpenGL at fullscreen mode 640x480;

Note: In each polygon draw the image of a bitmap.

1) Position of eye: (20, 20, 20)
2) Point of observation: (0, 0, 0)
3) Vector Up the camera: (-1, -1, 1)
4) Visual Angle: 45
5) Distance Far: 50
6) Near Distance: 0.1

7) The vertices of the polygon 1 are: (0, 0, 0), (1, 1, 0), (2, 0, 0)
with a bitmap 1 of 640x480. (occupying the area of ​​the polygon)

8> The vertices of the polygon 2 are: (0, 0, 5), (1, 1, 5), (2, 0, 5)
with a bitmap 2 of 320x200. (occupying the area of ​​the polygon)

The code (free pascal) for this program-problem would be helpful.
(please).
Any suggestions would help.

Thanks.

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mrBrown · 2011-06-23 09:01

Have you tried GLScene?

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carlejt · 2011-06-23 17:38

Hello

Thanks for responding. I've tried but I failed to install. I followed
the instructions in http://wiki.lazarus.freepascal.org/GLScene.

Actually I want to know what would be the code of the program the
problem I raised. It would be helpful.

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mrBrown · 2011-06-24 11:13

I think those instructions are a bit outdated.

Just download GLScene from www.glscene.org.

I downloaded the Snapshot for SVN revision 5593 last week and it
installed fine in lazarus 0.9.30.

From lazarus do Package -> open package file
and then select glscene_runtime.lpk in the /Lazarus directory of
GLScene (or the other one, don't remember). Lazarus will add the other
required packages automatically.

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Leledumbo · 2011-06-24 17:17

Try the OpenGL example, then try solving the problem yourself. When
stuck, post your code so far and explain what you have done and what's
missing.

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carlejt · 2011-06-24 21:23

I have followed the example TEXTURES Tutorial OpenGL but I can not
compile it. I have the library glut32.dll.

This is the example TEXTURES del tutorial OpenGL:


Code: [Select]
program textures;

{$mode objfpc}{$H+}

uses
  gl, glu, glut, ImagingOpenGL;

const
  AppWidth = 640;
  AppHeight = 480;
  LIST_OBJECT = 1;
 
var
  Tex1, Tex2: GLuint;
 
procedure InitializeGL;
begin
  glClearColor(0, 0, 0, 0);
  Tex1 := LoadGLTextureFromFile('ashwood.bmp');
  Tex2 := LoadGLTextureFromFile('Flare.bmp');
  glEnable(GL_TEXTURE_2D);
end;

procedure CreateList;
begin
  glNewList(LIST_OBJECT, GL_COMPILE);
    glBegin(GL_QUADS);
      glTexCoord2f(1, 0);
      glVertex3f( 2, 2, 0);
      glTexCoord2f(0, 0);
      glVertex3f(-2, 2, 0);
      glTexCoord2f(0, 1);
      glVertex3f(-2,-2, 0);
      glTexCoord2f(1, 1);
      glVertex3f( 2,-2, 0);
    glEnd;
  glEndList;
end;

procedure DrawGLScene; cdecl;
begin
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

  glLoadIdentity;
  glTranslatef(-5, 0, -15);
  glBindTexture(GL_TEXTURE_2D, Tex1);
  glCallList(LIST_OBJECT);

  glLoadIdentity;
  glTranslatef(0, 0, -15);
  glBindTexture(GL_TEXTURE_2D, Tex2);
  glCallList(LIST_OBJECT);

  glLoadIdentity;
  glTranslatef(5, 0, -15);
  glBindTexture(GL_TEXTURE_2D, Tex1);
  glCallList(LIST_OBJECT);

  glEnable(GL_BLEND);
  glBlendFunc(GL_ZERO, GL_SRC_COLOR);
  glLoadIdentity;
  glTranslatef(5, 0, -15);
  glBindTexture(GL_TEXTURE_2D, Tex2);
  glCallList(LIST_OBJECT);
  glDisable(GL_BLEND);

  glutSwapBuffers;
end;

procedure ReSizeGLScene(Width, Height: Integer); cdecl;
begin
  if Height = 0 then
    Height := 1;

  glViewport(0, 0, Width, Height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity;
  gluPerspective(45, Width / Height, 0.1, 1000);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity;
end;

procedure GLKeyboard(Key: Byte; X, Y: Longint); cdecl;
begin
  if Key = 27 then
  begin
    glDeleteLists(LIST_OBJECT, 1);
    Halt(0);
  end;
end;

procedure glutInitPascal(ParseCmdLine: Boolean);
var
  Cmd: array of PChar;
  CmdCount, I: Integer;
begin
  if ParseCmdLine then
    CmdCount := ParamCount + 1
  else
    CmdCount := 1;
  SetLength(Cmd, CmdCount);
  for I := 0 to CmdCount - 1 do
    Cmd[I] := PChar(ParamStr(I));
  glutInit(@CmdCount, @Cmd);
end;

var
  ScreenWidth, ScreenHeight: Integer;
begin
  glutInitPascal(True);
  glutInitDisplayMode(GLUT_DOUBLE or GLUT_RGB or GLUT_DEPTH);
  glutInitWindowSize(AppWidth, AppHeight);
  ScreenWidth := glutGet(GLUT_SCREEN_WIDTH);
  ScreenHeight := glutGet(GLUT_SCREEN_HEIGHT);
  glutInitWindowPosition((ScreenWidth - AppWidth) div 2, (ScreenHeight
- AppHeight) div 2);
  glutCreateWindow('OpenGL Tutorial :: Textures');

  InitializeGL;
  CreateList;

  glutDisplayFunc(@DrawGLScene);
  glutReshapeFunc(@ReSizeGLScene);
  glutKeyboardFunc(@GLKeyboard);

  glutMainLoop;
end.


Anyone know where to find these examples with the Vampyre Imaging
Library units for Free Pascal.

On page

http://imaginglib.sourceforge.net/index.php?page=down

Downloaded the Imaging0.26.4. What are the units for free pascal for
compile the code TEXTURES?

Not only is the unit ImagingOpenGL.

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Carver413 · 2011-06-25 05:24

I'm assuming that this is some sort of school project and that
learning modern opengl is not really on the agenda. so here is a site
that should help you learn the older more user friendly opengl that
most of us grew to love. 
http://www.freepascal-meets-sdl.net/
also you should check out this site as many people there use sdl and
opengl
http://www.pascalgamedevelopment.com/