Date: 02-16-2022
Return to Index
created by gbSnippets
'This example displays a rotating cube drawn using a display list.
'OpenGL provides a "display list" as a means of storing a sequence of drawing
'commands, Once the list of commands is saved, it can be called with a single
'statement. Also, the list can be used over and over again in the OpenGL application.
'Primary Code:
'First, the glNewList/glEndList commands are used to create the list.
'Between the two commands glNewList and glEndList, place drawing commands.
'Note that the display list is assigned a simple integer identifier.
Sub BuildDisplayList(ListNumber As Long)
glNewList iNumber, %gl_compile
glBegin %GL_QUADS
glColor3f 0.0, 1.0, 0.0
glVertex3f 1.0, 1.0, -1.0
glVertex3f -1.0, 1.0, -1.0
glVertex3f -1.0, 1.0, 1.0
glVertex3f 1.0, 1.0, 1.0
glEnd
glEndList
End Sub
'Then, where glBegin/glEnd would have gone in the DrawScene procedure, use the
'glCallList function to call the display list by its numberical identifier.
Sub DrawScene (dx As Single, dy As Single, dz As Single)
... usual..commands...
glCallList 1 'call the display list (where glBegin/glEnd would have gone)
SwapBuffers hDC 'display the buffer (image)
End Sub
'Compilable Example: (Jose Includes)
#Compiler PBWin 9, PBWin 10
#Compile EXE
#Dim All
%Unicode=1
#Include "win32api.inc"
#Include "gl.inc"
#Include "glu.inc"
%ID_Timer = 1000
Global hDlg, hDC, hRC As DWord
Global scalefactor As Single
Function PBMain() As Long
Dialog New Pixels, 0, "OpenGL Example",,, 320, 240,%WS_OverlappedWindow To hDlg
Dialog Show Modal hdlg Call dlgproc
End Function
CallBack Function dlgproc()
Local pt As Point
Local XDelta, YDelta as Single
Static SpinInWork,XLast,YLast As Long
Select Case CB.Msg
Case %WM_InitDialog : GetRenderContext
InitializeScene
SetTimer(hDlg, %ID_Timer, 50, %NULL)
ScaleFactor = 1
Case %WM_Timer : DrawScene 1,2,0 'redraw with rotation
Case %WM_Paint : DrawScene 0,0,0 'redraw with no rotation
Case %WM_Size : ResizeScene Lo(Word, CB.lParam), Hi(Word, CB.lParam)
DrawScene 0,0,0 'redraw with no rotation
Case %WM_Close : wglmakecurrent %null, %null 'unselect rendering context
wgldeletecontext hRC 'delete the rendering context
releasedc hDlg, hDC 'release device context
Case %WM_MouseWheel
Select Case Hi(Integer,CB.wParam)
Case > 0 : ScaleFactor = ScaleFactor + 0.1 : DrawScene 0,0,0
Case < 0 : ScaleFactor = ScaleFactor - 0.1 : DrawScene 0,0,0
End Select
Case %WM_SetCursor
Select Case Hi(Word, CB.lParam)
Case %WM_LButtonDown
GetCursorPos pt 'pt has xy screen coordinates
ScreenToClient hDlg, pt 'pt now has dialog client coordinates
If pt.y < 0 Then Exit Select
KillTimer CB.Hndl, %ID_Timer
SpinInWork = 1
XLast = Pt.x
YLast = Pt.y
Case %WM_MouseMove
If SpinInWork Then
GetCursorPos pt 'pt has xy screen coordinates
ScreenToClient hDlg, pt 'pt now has dialog client coordinates
If pt.y < 0 Then Exit Select
XDelta = XLast - Pt.x
YDelta = YLast - Pt.y
DrawScene -YDelta, -XDelta, 0
XLast = pt.x
YLast = pt.y
End If
Case %WM_LButtonUp
SetTimer(hDlg, %ID_Timer, 50, %NULL)
SpinInWork = 0
End Select
End Select
End Function
Sub GetRenderContext
Local pfd As PIXELFORMATDESCRIPTOR 'pixel format properties for device context
pfd.nSize = SizeOf(PIXELFORMATDESCRIPTOR)
pfd.nVersion = 1
pfd.dwFlags = %pfd_draw_to_window Or %pfd_support_opengl Or %pfd_doublebuffer
pfd.dwlayermask = %pfd_main_plane
pfd.iPixelType = %pfd_type_rgba
pfd.ccolorbits = 24
pfd.cdepthbits = 24
hDC = GetDC(hDlg) 'DC for dialog
SetPixelFormat(hDC, ChoosePixelFormat(hDC, pfd), pfd) 'set properties of device context
hRC = wglCreateContext (hDC) 'get rendering context
wglMakeCurrent hDC, hRC 'make the RC current
End Sub
Sub InitializeScene
glClearColor 0,0,0,0 'sets color to be used with glClear
glClearDepth 1 'sets zvalue to be used with glClear
glEnable %gl_depth_test 'enable depth testing
glHint %gl_perspective_correction_hint, %gl_nicest 'best quality rendering
BuildDisplayList 1
End Sub
Sub ResizeScene (w As Long, h As Long)
glViewport 0, 0, w, h 'resize viewport to match window size
glMatrixMode %gl_projection 'select the projection matrix
glLoadIdentity 'reset the projection matrix
gluPerspective 45, w/h, 0.1, 100 'set frustum using viewport aspect ratio
glMatrixMode %gl_modelview 'select the modelview matrix
End Sub
Sub DrawScene (dx As Single, dy As Single, dz As Single)
Static anglex, angley, anglez As Single
glClear %gl_color_buffer_bit Or %gl_depth_buffer_bit 'clear buffers
glLoadIdentity 'clear the modelview matrix
gluLookAt 0,0,6,0,0,0,0,1,0
glScalef scalefactor, scalefactor, scalefactor
anglex = anglex + dx : glRotatef anglex, 1,0,0
angley = angley + dy : glRotatef angley, 0,1,0
anglez = anglez + dz : glRotatef anglez, 0,0,1
glCallList 1
SwapBuffers hDC 'display the buffer (image)
End Sub
Sub BuildDisplayList (ListNumber As Long)
glNewList ListNumber, %gl_compile
glBegin %gl_line_loop
glVertex3f -0.5, -0.5, -0.5 '1234
glVertex3f -0.5, 0.5, -0.5
glVertex3f 0.5, 0.5, -0.5
glVertex3f 0.5, -0.5, -0.5
glEnd
glBegin %gl_line_loop
glVertex3f -0.5, -0.5, 0.5 '5678
glVertex3f -0.5, 0.5, 0.5
glVertex3f 0.5, 0.5, 0.5
glVertex3f 0.5, -0.5, 0.5
glEnd
glBegin %gl_lines
glVertex3f -0.5, -0.5, -0.5 '15
glVertex3f -0.5, -0.5, 0.5
glVertex3f -0.5, 0.5, -0.5 '26
glVertex3f -0.5, 0.5, 0.5
glVertex3f 0.5, 0.5, -0.5 '37
glVertex3f 0.5, 0.5, 0.5
glVertex3f 0.5, -0.5, -0.5 '48
glVertex3f 0.5, -0.5, 0.5
glEnd
glEndList
End Sub
'gbs_00609
'Date: 03-10-2012
http://www.garybeene.com/sw/gbsnippets.htm