Demo ogl_axis_aligned_billboard
Demo 3 of 19 in category CodeSampler
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#-----------------------------------------------------------------------------
# Name: ogl_axis_aligned_billboard.cpp
# Author: Kevin Harris (kevin@codesampler.com)
# Last Modified: 02/01/05
# Description: An example of axis aligned billboarding.
#
# Control Keys: F1 - Toggle billboarding
# Up - View moves forward
# Down - View moves backward
# Left - View strafes left
# Right - View strafes Right
# Left Mouse - Perform looking
# Mouse - Look about the scene
#-----------------------------------------------------------------------------
#
# Original C++ code by Kevin Harris (kevin@codesampler.com)
# See www.codesampler.com for the original files
# OpenGL samples page 8: Axis-Aligned Billboards
#
# Modified for Tcl3D by Paul Obermeier 2007/03/10
# See www.tcl3d.org for the Tcl3D extension.
package require Tk
package require tcl3d
# Font to be used in the Tk listbox.
set g_listFont {-family {Courier} -size 10}
set g_WinWidth 640
set g_WinHeight 480
set g_bBillboard 1
set g_fMoveSpeed 25.0
set g_vEye [tcl3dVectorFromArgs GLfloat 0.0 0.0 5.0] ; # Eye Position
set g_vLook [tcl3dVectorFromArgs GLfloat 0.0 0.0 -1.0] ; # Look Vector
set g_vUp [tcl3dVectorFromArgs GLfloat 0.0 1.0 0.0] ; # Up Vector
set g_vRight [tcl3dVectorFromArgs GLfloat 1.0 0.0 0.0] ; # Right Vector
set g_StopWatch [tcl3dNewSwatch]
tcl3dStartSwatch $g_StopWatch
set ::g_LastMousePosX(1) 0
set ::g_LastMousePosY(1) 0
set g_tmpMat [tcl3dVector GLfloat 16]
set g_tmpVec [tcl3dVector GLfloat 3]
# Determine the directory of this script.
set g_scriptDir [file dirname [info script]]
# 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
}
}
# Update last line of usage messages.
proc UpdateMsg { msgStr } {
if { [winfo exists .fr.usage] } {
.fr.usage configure -state normal
.fr.usage delete end
.fr.usage insert end $msgStr
.fr.usage configure -state disabled
}
}
proc SetMouseInput { x y } {
set ::g_LastMousePosX(1) $x
set ::g_LastMousePosY(1) $y
}
proc GetMouseInput { x y } {
set nXDiff [expr ($x - $::g_LastMousePosX(1))]
set nYDiff [expr ($y - $::g_LastMousePosY(1))]
if { $nYDiff != 0 } {
tcl3dMatfRotate [expr -1.0*$nYDiff / 3.0] $::g_vRight $::g_tmpMat
tcl3dMatfTransformVector $::g_vLook $::g_tmpMat $::g_vLook
tcl3dMatfTransformVector $::g_vUp $::g_tmpMat $::g_vUp
}
if { $nXDiff != 0 } {
set vec [tcl3dVectorFromArgs GLfloat 0 1 0]
tcl3dMatfRotate [expr -1.0*$nXDiff / 3.0] $vec $::g_tmpMat
tcl3dMatfTransformVector $::g_vLook $::g_tmpMat $::g_vLook
tcl3dMatfTransformVector $::g_vUp $::g_tmpMat $::g_vUp
$vec delete
}
set ::g_LastMousePosX(1) $x
set ::g_LastMousePosY(1) $y
.fr.toglwin postredisplay
}
proc MoveForward {} {
tcl3dVec3fScale [expr {-1.0 * $::g_fMoveSpeed * $::g_fElapsedTime}] $::g_vLook $::g_tmpVec
tcl3dVec3fSubtract $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc MoveBackward {} {
tcl3dVec3fScale [expr {-1.0 * $::g_fMoveSpeed * $::g_fElapsedTime}] $::g_vLook $::g_tmpVec
tcl3dVec3fAdd $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc MoveLeft {} {
tcl3dVec3fScale [expr {$::g_fMoveSpeed * $::g_fElapsedTime}] $::g_vRight $::g_tmpVec
tcl3dVec3fSubtract $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc MoveRight {} {
tcl3dVec3fScale [expr {$::g_fMoveSpeed * $::g_fElapsedTime}] $::g_vRight $::g_tmpVec
tcl3dVec3fAdd $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc MoveUp {} {
$::g_tmpVec set 0 0
$::g_tmpVec set 1 [expr {$::g_fMoveSpeed * $::g_fElapsedTime}]
$::g_tmpVec set 2 0
tcl3dVec3fAdd $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc MoveDown {} {
$::g_tmpVec set 0 0
$::g_tmpVec set 1 [expr {$::g_fMoveSpeed * $::g_fElapsedTime}]
$::g_tmpVec set 2 0
tcl3dVec3fSubtract $::g_vEye $::g_tmpVec $::g_vEye
.fr.toglwin postredisplay
}
proc ToggleBillboard {} {
set ::g_bBillboard [expr ! $::g_bBillboard]
if { $::g_bBillboard } {
UpdateMsg "Billboarding is on"
} else {
UpdateMsg "Billboarding is off"
}
.fr.toglwin postredisplay
}
proc LoadTexture {} {
# For the billboard poly, load a texture of a maple tree. We'll use a
# .tga file for this image so we can use an alpha channel.
set texName [file join $::g_scriptDir "maple_tree.tga"]
set retVal [catch {set phImg [image create photo -file $texName]} err1]
if { $retVal != 0 } {
error "Error reading image $texName ($err1)"
} else {
set w [image width $phImg]
set h [image height $phImg]
set n [tcl3dPhotoChans $phImg]
set pTextureImage [tcl3dVectorFromPhoto $phImg]
image delete $phImg
}
set ::g_treeTextureID [tcl3dVector GLuint 1]
glGenTextures 1 $::g_treeTextureID
glBindTexture GL_TEXTURE_2D [$::g_treeTextureID get 0]
glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER $::GL_LINEAR
glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER $::GL_LINEAR
glTexImage2D GL_TEXTURE_2D 0 $::GL_RGBA $w $h 0 $::GL_RGBA GL_UNSIGNED_BYTE $pTextureImage
$pTextureImage delete
# For the ground poly, load a texture of some grass from a regular bmp file.
set texName [file join $::g_scriptDir "grass.bmp"]
set retVal [catch {set phImg [image create photo -file $texName]} err1]
if { $retVal != 0 } {
error "Error reading image $texName ($err1)"
} else {
set w [image width $phImg]
set h [image height $phImg]
set n [tcl3dPhotoChans $phImg]
set pTextureImage [tcl3dVectorFromPhoto $phImg]
image delete $phImg
}
set ::g_grassTextureID [tcl3dVector GLuint 1]
glGenTextures 1 $::g_grassTextureID
glBindTexture GL_TEXTURE_2D [$::g_grassTextureID get 0]
glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER $::GL_LINEAR
glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER $::GL_LINEAR
glTexImage2D GL_TEXTURE_2D 0 3 $w $h 0 $::GL_RGBA GL_UNSIGNED_BYTE $pTextureImage
$pTextureImage delete
}
proc CreateCallback { toglwin } {
glClearColor 0.35 0.53 0.7 1.0
glEnable GL_TEXTURE_2D
glEnable GL_DEPTH_TEST
glMatrixMode GL_PROJECTION
glLoadIdentity
gluPerspective 45.0 [expr double($::g_WinWidth) / double($::g_WinHeight)] 0.1 100.0
LoadTexture
}
proc ReshapeCallback { toglwin { w -1 } { h -1 } } {
set w [$toglwin width]
set h [$toglwin height]
glViewport 0 0 $w $h
glMatrixMode GL_PROJECTION
glLoadIdentity
gluPerspective 45.0 [expr double($w)/double($h)] 0.1 100.0
}
#-----------------------------------------------------------------------------
# Name : UpdateViewMatrix
# Desc : Builds a view matrix suitable for OpenGL.
#
# Here's what the final view matrix should look like:
#
# | rx ry rz -(r.e) |
# | ux uy uz -(u.e) |
# | -lx -ly -lz (l.e) |
# | 0 0 0 1 |
#
# Where r = Right vector
# u = Up vector
# l = Look vector
# e = Eye position in world space
# . = Dot-product operation
#
#-----------------------------------------------------------------------------
proc UpdateViewMatrix {} {
tcl3dMatfIdentity $::g_tmpMat
tcl3dVec3fNormalize $::g_vLook
tcl3dVec3fCrossProduct $::g_vLook $::g_vUp $::g_vRight
tcl3dVec3fNormalize $::g_vRight
tcl3dVec3fCrossProduct $::g_vRight $::g_vLook $::g_vUp
tcl3dVec3fNormalize $::g_vUp
set rightX [$::g_vRight get 0]
set rightY [$::g_vRight get 1]
set rightZ [$::g_vRight get 2]
set upX [$::g_vUp get 0]
set upY [$::g_vUp get 1]
set upZ [$::g_vUp get 2]
set lookX [$::g_vLook get 0]
set lookY [$::g_vLook get 1]
set lookZ [$::g_vLook get 2]
$::g_tmpMat set 0 $rightX
$::g_tmpMat set 1 $upX
$::g_tmpMat set 2 [expr -1.0 * $lookX]
$::g_tmpMat set 3 0
$::g_tmpMat set 4 $rightY
$::g_tmpMat set 5 $upY
$::g_tmpMat set 6 [expr -1.0 * $lookY]
$::g_tmpMat set 7 0
$::g_tmpMat set 8 $rightZ
$::g_tmpMat set 9 $upZ
$::g_tmpMat set 10 [expr -1.0 * $lookZ]
$::g_tmpMat set 11 0
$::g_tmpMat set 12 [expr -1.0 * [tcl3dVec3fDotProduct $::g_vRight $::g_vEye]]
$::g_tmpMat set 13 [expr -1.0 * [tcl3dVec3fDotProduct $::g_vUp $::g_vEye]]
$::g_tmpMat set 14 [expr 1.0 * [tcl3dVec3fDotProduct $::g_vLook $::g_vEye]]
$::g_tmpMat set 15 1
set viewList [tcl3dVectorToList $::g_tmpMat 16]
glMultMatrixf $viewList
}
proc BuildAxisAlignedBBMatrix { m x y z } {
set pi 3.141592654
set theta [expr { -180.0 * atan2 ([$m get 8], [$m get 10]) / $pi }]
set d [expr { $x*$x + $y*$y + $z*$z }]
set ct [expr { cos([tcl3dDegToRad $theta]) }]
set st [expr { sin([tcl3dDegToRad $theta]) }]
# Normalize
if { $d > 0.0 } {
set d [expr { 1.0/$d }]
set x [expr { $x * $d }]
set y [expr { $y * $d }]
set z [expr { $z * $d }]
}
# Create an identity matrix as a Tcl list.
set ml [list \
1.0 0.0 0.0 0.0 \
0.0 1.0 0.0 0.0 \
0.0 0.0 1.0 0.0 \
0.0 0.0 0.0 1.0 \
]
#---------------------------------------------
# R = uu' + cos(theta)*(I-uu') + sin(theta)*S
#
# S = 0 -z y u' = (x, y, z)
# z 0 -x
# -y x 0
#---------------------------------------------
lset ml 0 [expr { $x*$x + $ct*(1-$x*$x) + $st*0 }]
lset ml 4 [expr { $x*$y + $ct*(0-$x*$y) + $st*-1.0*$z }]
lset ml 8 [expr { $x*$z + $ct*(0-$x*$z) + $st*$y }]
lset ml 1 [expr { $y*$x + $ct*(0-$y*$x) + $st*$z }]
lset ml 5 [expr { $y*$y + $ct*(1-$y*$y) + $st*0 }]
lset ml 9 [expr { $y*$z + $ct*(0-$y*$z) + $st*-1.0*$x }]
lset ml 2 [expr { $z*$x + $ct*(0-$z*$x) + $st*-1.0*$y }]
lset ml 6 [expr { $z*$y + $ct*(0-$z*$y) + $st*$x }]
lset ml 10 [expr { $z*$z + $ct*(1-$z*$z) + $st*0 }]
return $ml
}
proc DisplayCallback { toglwin } {
set startTime [tcl3dLookupSwatch $::g_StopWatch]
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] [$toglwin height]
glMatrixMode GL_MODELVIEW
glLoadIdentity
UpdateViewMatrix
# Render Floor Poly
glBindTexture GL_TEXTURE_2D [$::g_grassTextureID get 0]
glBegin GL_POLYGON
glTexCoord2f 0.0 0.0
glVertex3f -2.0 -1.0 -2.0
glTexCoord2f 1.0 0.0
glVertex3f 2.0 -1.0 -2.0
glTexCoord2f 1.0 1.0
glVertex3f 2.0 -1.0 2.0
glTexCoord2f 0.0 1.0
glVertex3f -2.0 -1.0 2.0
glEnd
# Render Billboard poly
if { $::g_bBillboard } {
set mat [tcl3dVector GLfloat 16]
glGetFloatv GL_MODELVIEW_MATRIX $mat
# Do billboard rotation about the y axis
set matList [BuildAxisAlignedBBMatrix $mat 0.0 1.0 0.0]
glMultMatrixf $matList
$mat delete
}
glEnable GL_BLEND
glBlendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
glEnable GL_ALPHA_TEST
glAlphaFunc GL_GREATER 0
glBindTexture GL_TEXTURE_2D [$::g_treeTextureID get 0]
glBegin GL_POLYGON
glTexCoord2f 0.0 0.0
glVertex3f -1.0 -1.0 0.0
glTexCoord2f 1.0 0.0
glVertex3f 1.0 -1.0 0.0
glTexCoord2f 1.0 1.0
glVertex3f 1.0 1.0 0.0
glTexCoord2f 0.0 1.0
glVertex3f -1.0 1.0 0.0
glEnd
glDisable GL_BLEND
glDisable GL_ALPHA_TEST
$toglwin swapbuffers
set endTime [tcl3dLookupSwatch $::g_StopWatch]
set ::g_fElapsedTime [expr {$endTime - $startTime}]
}
proc Cleanup {} {
if { [info exists ::g_treeTextureID] } {
glDeleteTextures 1 [$::g_treeTextureID get 0]
$::g_treeTextureID delete
}
if { [info exists ::g_grassTextureID] } {
glDeleteTextures 1 [$::g_grassTextureID get 0]
$::g_grassTextureID delete
}
$::g_tmpMat delete
$::g_tmpVec delete
tcl3dDeleteSwatch $::g_StopWatch
foreach var [info globals g_*] {
uplevel #0 unset $var
}
}
proc ExitProg {} {
exit
}
frame .fr
pack .fr -expand 1 -fill both
togl .fr.toglwin -width $g_WinWidth -height $g_WinHeight \
-double true -depth true -alpha true \
-createcommand CreateCallback \
-reshapecommand ReshapeCallback \
-displaycommand DisplayCallback
listbox .fr.usage -font $::g_listFont -height 6
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: CodeSampler's Axis Aligned Billboard"
# Watch For ESC Key And Quit Messages
wm protocol . WM_DELETE_WINDOW "ExitProg"
bind . <Key-Escape> "ExitProg"
bind . <Key-Up> "MoveForward"
bind . <Key-Down> "MoveBackward"
bind . <Key-Left> "MoveLeft"
bind . <Key-Right> "MoveRight"
bind . <Key-Home> "MoveUp"
bind . <Key-End> "MoveDown"
bind . <Key-F1> "ToggleBillboard"
bind .fr.toglwin <1> "SetMouseInput %x %y"
bind .fr.toglwin <B1-Motion> "GetMouseInput %x %y"
.fr.usage insert end "Key-Escape Exit"
.fr.usage insert end "Key-F1 Toggle billboarding"
.fr.usage insert end "Key-Up|Down View moves forward|backward"
.fr.usage insert end "Key-Left|Right View strafes to the left|right"
.fr.usage insert end "Key-Home|End View elevates up|down"
.fr.usage insert end "Billboarding messages"
.fr.usage configure -state disabled
UpdateMsg "Billboarding is on"
PrintInfo [tcl3dOglGetInfoString]
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