Demo 3 of 68 in category RedBook
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# aargb.tcl
#
# An example of the OpenGL red book modified to work with Tcl3D.
# The original C sources are Copyright (c) 1993-2003, Silicon Graphics, Inc.
# The Tcl3D sources are Copyright (c) 2005-2022, Paul Obermeier.
# See file LICENSE for complete license information.
#
# This program draws shows how to draw anti-aliased lines. It draws
# two diagonal lines to form an X; when 'r' is typed in the window,
# the lines are rotated in opposite directions.
package require tcl3d
set rotAngle 0.0
# Font to be used in the Tk listbox.
set listFont {-family {Courier} -size 10}
# Show errors occuring in the Togl callbacks.
proc bgerror { msg } {
tk_messageBox -icon error -type ok -message "Error: $msg\n\n$::errorInfo"
exit
}
# Print info message into widget a the bottom of the window.
proc PrintInfo { msg } {
if { [winfo exists .fr.info] } {
.fr.info configure -text $msg
}
}
# Initialize antialiasing for RGBA mode, including alpha
# blending, hint, and line width. Print out implementation
# specific info on line width granularity and width.
#
proc CreateCallback { toglwin } {
global lw_granularity lw_range
set lw_granularity [tcl3dOglGetFloatState GL_LINE_WIDTH_GRANULARITY 2]
set lw_range [tcl3dOglGetFloatState GL_LINE_WIDTH_RANGE 2]
glEnable GL_LINE_SMOOTH
glEnable GL_BLEND
glBlendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
glHint GL_LINE_SMOOTH_HINT GL_DONT_CARE
glLineWidth 1.5
glClearColor 0.0 0.0 0.0 0.0
}
# Draw 2 diagonal lines to form an X
#
proc DisplayCallback { toglwin } {
global rotAngle
glClear GL_COLOR_BUFFER_BIT
# Viewport command is not really needed, but has been inserted for
# Mac OSX. Presentation framework (Tk) does not send a reshape event,
# when switching from one demo to another.
glViewport 0 0 [$toglwin width] [$toglwin height]
glColor3f 0.0 1.0 0.0
glPushMatrix
glRotatef [expr -1.0 * $rotAngle] 0.0 0.0 0.1
glBegin GL_LINES
glVertex2f -0.5 0.5
glVertex2f 0.5 -0.5
glEnd
glPopMatrix
glColor3f 0.0 0.0 1.0
glPushMatrix
glRotatef $rotAngle 0.0 0.0 0.1
glBegin GL_LINES
glVertex2f 0.5 0.5
glVertex2f -0.5 -0.5
glEnd
glPopMatrix
glFlush
$toglwin swapbuffers
}
proc ReshapeCallback { toglwin { w -1 } { h -1 } } {
set w [$toglwin width]
set h [$toglwin height]
glViewport 0 0 $w $h
glMatrixMode GL_PROJECTION
glLoadIdentity
if { $w <= $h } {
gluOrtho2D -1.0 1.0 [expr -1.0*$h/$w] [expr 1.0*$h/$w]
} else {
gluOrtho2D [expr -1.0*$w/$h] [expr 1.0*$w/$h] -1.0 1.0
}
glMatrixMode GL_MODELVIEW
glLoadIdentity
}
proc IncrRotAngle {} {
set ::rotAngle [expr $::rotAngle + 20.0]
if { $::rotAngle >= 360.0 } {
set ::rotAngle 0.0
}
.fr.toglwin postredisplay
}
frame .fr
pack .fr -expand 1 -fill both
togl .fr.toglwin -width 200 -height 200 -double true \
-createcommand CreateCallback \
-reshapecommand ReshapeCallback \
-displaycommand DisplayCallback
listbox .fr.usage -font $::listFont -height 4
label .fr.info
grid .fr.toglwin -row 0 -column 0 -sticky news
grid .fr.usage -row 1 -column 0 -sticky news
grid .fr.info -row 2 -column 0 -sticky news
grid rowconfigure .fr 0 -weight 1
grid columnconfigure .fr 0 -weight 1
wm title . "Tcl3D demo: OpenGL Red Book example aargb"
bind . <Key-r> "IncrRotAngle"
bind . <Key-Escape> "exit"
.fr.usage insert end "Key-r Rotate"
.fr.usage insert end "Key-Escape Exit"
.fr.usage insert end "GL_LINE_WIDTH_GRANULARITY: [lindex $lw_granularity 0]"
.fr.usage insert end "GL_LINE_WIDTH_RANGE: [lindex $lw_range 0] [lindex $lw_range 1]"
.fr.usage configure -state disabled
PrintInfo [tcl3dOglGetInfoString]
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