Demo 65 of 68 in category RedBook
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# trim.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 a NURBS surface in the shape of a
# symmetrical hill, using both a NURBS curve and pwl
# (piecewise linear) curve to trim part of the surface.
package require tcl3d
# 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
}
}
#
# Initializes the control points of the surface to a small hill.
# The control points range from -3 to +3 in x, y, and z
#
proc init_surface {} {
global ctlpoints
for { set u 0 } { $u < 4 } { incr u } {
for { set v 0 } { $v < 4 } { incr v } {
lappend ctlpoints { 0.0 0.0 0.0 }
}
}
for { set u 0 } { $u < 4 } { incr u } {
for { set v 0 } { $v < 4 } { incr v } {
lset ctlpoints [expr $u * 4 + $v] 0 [expr 2.0*(double($u) - 1.5)]
lset ctlpoints [expr $u * 4 + $v] 1 [expr 2.0*(double($v) - 1.5)]
if { ($u == 1 || $u == 2) && ($v == 1 || $v == 2) } {
lset ctlpoints [expr $u *4 + $v] 2 3.0
} else {
lset ctlpoints [expr $u *4 + $v] 2 -3.0
}
}
}
}
# Initialize material property and depth buffer.
#
proc CreateCallback { toglwin } {
global theNurb
set mat_diffuse { 0.7 0.7 0.7 1.0 }
set mat_specular { 1.0 1.0 1.0 1.0 }
set mat_shininess { 100.0 }
glClearColor 0.0 0.0 0.0 0.0
glMaterialfv GL_FRONT GL_DIFFUSE $mat_diffuse
glMaterialfv GL_FRONT GL_SPECULAR $mat_specular
glMaterialfv GL_FRONT GL_SHININESS $mat_shininess
glEnable GL_LIGHTING
glEnable GL_LIGHT0
glEnable GL_DEPTH_TEST
glEnable GL_AUTO_NORMAL
glEnable GL_NORMALIZE
init_surface
set theNurb [gluNewNurbsRenderer]
gluNurbsProperty $theNurb GLU_SAMPLING_TOLERANCE 25.0
gluNurbsProperty $theNurb GLU_DISPLAY_MODE $::GLU_FILL
}
proc DisplayCallback { toglwin } {
global theNurb
global ctlpoints
set knots {0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0}
# counter clockwise
set edgePt {{0.0 0.0} {1.0 0.0} {1.0 1.0} {0.0 1.0} {0.0 0.0}}
# clockwise
set curvePt {{0.25 0.5} {0.25 0.75} {0.75 0.75} {0.75 0.5}}
set curveKnots {0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0}
# clockwise
set pwlPt {{0.75 0.5} {0.5 0.25} {0.25 0.5}}
glClear [expr $::GL_COLOR_BUFFER_BIT | $::GL_DEPTH_BUFFER_BIT]
# Viewport command is not really needed, but has been inserted for
# Mac OSX. Presentation framework (Tk) does not send a reshape event,
# when switching from one demo to another.
glViewport 0 0 [$toglwin width] [$toglwin height]
glPushMatrix
glRotatef 330.0 1.0 0.0 0.0
glScalef 0.5 0.5 0.5
gluBeginSurface $theNurb
gluNurbsSurface $theNurb 8 $knots 8 $knots \
[expr 4 * 3] 3 [join $ctlpoints] \
4 4 GL_MAP2_VERTEX_3
gluBeginTrim $theNurb
gluPwlCurve $theNurb 5 [join $edgePt] 2 GLU_MAP1_TRIM_2
gluEndTrim $theNurb
gluBeginTrim $theNurb
gluNurbsCurve $theNurb 8 $curveKnots 2 \
[join $curvePt] 4 GLU_MAP1_TRIM_2
gluPwlCurve $theNurb 3 [join $pwlPt] 2 GLU_MAP1_TRIM_2
gluEndTrim $theNurb
gluEndSurface $theNurb
glPopMatrix
glFlush
$toglwin swapbuffers
}
proc ReshapeCallback { toglwin { w -1 } { h -1 } } {
set w [$toglwin width]
set h [$toglwin height]
glViewport 0 0 $w $h
glMatrixMode GL_PROJECTION
glLoadIdentity
gluPerspective 45.0 [expr double($w)/double($h)] 3.0 8.0
glMatrixMode GL_MODELVIEW
glLoadIdentity
glTranslatef 0.0 0.0 -5.0
}
frame .fr
pack .fr -expand 1 -fill both
togl .fr.toglwin -width 500 -height 500 -double true -depth true \
-createcommand CreateCallback \
-reshapecommand ReshapeCallback \
-displaycommand DisplayCallback
listbox .fr.usage -font $::listFont -height 1
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 trim"
bind . <Key-Escape> "exit"
.fr.usage insert end "Key-Escape Exit"
.fr.usage configure -state disabled
PrintInfo [tcl3dOglGetInfoString]
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