Graphics Reference
In-Depth Information
The color dodge operation involves a divide instead of a multiply and
involves the inverse rather than the original of the second image. Again,
some clamping may be needed.
vec3 target = argb/(vec3(1. - brgb);
Implement both the color burn and dodge operations.
16.
Modify the burn-through transition to replace the RGB average value
with the computed luminance. Can you see any subjective difference
between these two transitions? Discuss why you think the difference, or
lack of difference, you see is reasonable.
17.
In a variation on the break-through transition, create a systematic gray-
scale patern texture and use that to control the selection of the image for
each pixel. Look at the selection of transitions available in Powerpoint
and identify the transitions that can be implemented by this approach.
18.
In the break-through transition discussion, we said that you could actu-
ally display the noise texture used to control which image is presented
at each stage of the transi-tion. Do this. Then capture one frame part way
through the transition and compare that capture to the noise texture to
see if you can identify the texture's action in the transition.
19.
In the break-through transition discussion, Figure 11.33 shows how you
can create an output image from the noise texture, by assigning the same
value to all three color components. What if you assign
nv[0]
to red,
nv[1]
to green, and
nv[2]
to blue? What do you get? Why?
20.
If you declare a variable
uniform float Timer;
then
glman
will fill it with a value from 0. to 1. over the course of 10 sec-
onds. Try using
Timer
instead of
uT
in the image transitions to create an
animated effect.
