Glut Coordinate System

Used in keyboard and mouse callbacks

x

y

w

h[window]

Fall 2013 revised 2

Recall OpenGL Rendering Pipeline

stages of vertex transformation

OpenGL NDC (normalized device coordinate)

x

y z

[-1,1]2 × [0,1]depth range

Near (0)

Far (1)

Note: this is a left-hand coordinate system!

Fall 2013 revised 4

Recall OpenGL Rendering Pipeline

stages of vertex transformation

OpenGL Window Coordinates

x

y z

[0,1]2

Near (0)

Far (1)

Use Mouse to Pick 2D World

x

y

xmin xmax

(mx, my)

(x, y)

0

0

minmax

min

w

mx

xx

xx

w

x

Keep all terms positive

in the formula

Use Mouse to Pick 2D World

x

y

ymin

ymax

(mx, my)

(x, y)

h

myh

yy

yy

minmax

min

h

Length ratio: take positive

valuesy

Summary

0

0

minmax

min

w

mx

xx

xx

h

myh

yy

yy

minmax

min

minmaxmin xxw

mxxx

minmaxmin yyh

myhyy