occt/tests/v3d/glsl/phong_sides

puts "========"
puts "Per-pixel lighting using GLSL program (Phong shading), check lighting of back faces"
puts "========"

# create box
box b 1 2 3
explode b F

# draw box
vinit View1
vclear
vsetdispmode 1
vaxo
vdisplay b_1 b_2
vfit
vrotate 0.2 0.0 0.0

# take snapshot with fixed pipeline
vdump $::imagedir/${::casename}_OFF.png
set aColorB [vreadpixel 150 150 rgb name]
set aColorF [vreadpixel 250 250 rgb name]
if { "$aColorB" != "$aColorF"} {
  puts "Error: front/back colors are different!"
}
set aColorFixed $aColorF

# activate phong shader
vshaderprog phong
set aColorB [vreadpixel 150 150 rgb name]
set aColorF [vreadpixel 250 250 rgb name]
if { "$aColorB" != "$aColorF"} {
  puts "Error: front/back colors are different!"
}

if { "$aColorF" != "$aColorFixed"} {
  puts "Error: colors are different!"
}