Demo 43 of 68 in category RedBook
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# picksquare.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.
#
# Use of multiple names and picking are demonstrated.
# A 3x3 grid of squares is drawn. When the left mouse
# button is pressed, all squares under the cursor position
# have their color changed.
package require tcl3d
tcl3dConsoleCreate .tcl3dOutputConsole "# " "Picksquare Output"
set BUFSIZE 512
set selectBuffer [tcl3dVector GLuint $::BUFSIZE]
# 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
}
}
# Clear color value for every square on the board
proc CreateCallback { toglwin } {
set ::board {}
for { set i 0 } { $i < 3 } { incr i } {
for { set j 0 } { $j < 3 } { incr j } {
lappend ::board 0
}
}
glClearColor 0.0 0.0 0.0 0.0
}
# The nine squares are drawn. In selection mode, each
# square is given two names: one for the row and the
# other for the column on the grid. The color of each
# square is determined by its position on the grid, and
# the value in the board[][] array.
#
proc drawSquares { mode } {
for { set i 0 } { $i < 3 } { incr i } {
if { $mode == $::GL_SELECT } {
glLoadName $i
}
for { set j 0 } { $j < 3 } { incr j } {
if { $mode == $::GL_SELECT } {
glPushName $j
}
glColor3f [expr $i/3.0] [expr $j/3.0] \
[expr [lindex $::board [expr $i*3 + $j]]/3.0]
glRecti $i $j [expr $i+1] [expr $j+1]
if { $mode == $::GL_SELECT } {
glPopName
}
}
}
}
# processHits prints out the contents of the
# selection array.
#
proc processHits { hits } {
set count 0
puts "hits = $hits"
for { set i 0 } { $i < $hits } { incr i } {
set names [$::selectBuffer get $count]
puts " number of names for hit = $names"
incr count
puts -nonewline [format " z1 is %g;" \
[expr double ([$::selectBuffer get $count]) / 0x7fffffff]]
incr count
puts [format " z2 is %g" \
[expr double ([$::selectBuffer get $count]) / 0x7fffffff]]
incr count
puts -nonewline " names are "
for { set j 0 } { $j < $names } { incr j } {
set val [$::selectBuffer get $count]
puts -nonewline [format "%d " $val]
if { $j == 0 } {
set ii $val
} elseif { $j == 1 } {
set jj $val
}
incr count
}
puts ""
set bval [expr ([lindex $::board [expr $ii*3 + $jj]] + 1) % 3]
lset ::board [expr $ii*3 + $jj] $bval
}
}
# pickSquares() sets up selection mode, name stack,
# and projection matrix for picking. Then the
# objects are drawn.
#
proc pickSquares { x y } {
set viewport [tcl3dVector GLint 4]
glGetIntegerv GL_VIEWPORT $viewport
glSelectBuffer $::BUFSIZE $::selectBuffer
glRenderMode GL_SELECT
glInitNames
glPushName 0
glMatrixMode GL_PROJECTION
glPushMatrix
glLoadIdentity
# create 5x5 pixel picking region near cursor location
gluPickMatrix $x [expr [$viewport get 3] - $y] 5.0 5.0 $viewport
gluOrtho2D 0.0 3.0 0.0 3.0
drawSquares $::GL_SELECT
glMatrixMode GL_PROJECTION
glPopMatrix
glFlush
set hits [glRenderMode GL_RENDER]
processHits $hits
$viewport delete
.fr.toglwin postredisplay
}
proc DisplayCallback { toglwin } {
glClear GL_COLOR_BUFFER_BIT
# Viewport command is not really needed, but has been inserted for
# Mac OSX. Presentation framework (Tk) does not send a reshape event,
# when switching from one demo to another.
glViewport 0 0 [$toglwin width] [$toglwin height]
drawSquares $::GL_RENDER
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
gluOrtho2D 0.0 3.0 0.0 3.0
glMatrixMode GL_MODELVIEW
glLoadIdentity
}
frame .fr
pack .fr -expand 1 -fill both
togl .fr.toglwin -width 400 -height 400 -double true \
-createcommand CreateCallback \
-reshapecommand ReshapeCallback \
-displaycommand DisplayCallback
listbox .fr.usage -font $::listFont -height 2
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 picksquare"
bind . <Key-Escape> "exit"
bind .fr.toglwin <1> "pickSquares %x %y"
.fr.usage insert end "Key-Escape Exit"
.fr.usage insert end "Mouse-L Get pick results"
.fr.usage configure -state disabled
PrintInfo [tcl3dOglGetInfoString]
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