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VHELP.TXT
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1993-11-03
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View Dialog Help
for
Picaso Version 1.0
Location: This is where the view port location is in 3D space.
Refer to the coordinate system above the example for
details about the coordinate system.
Direction: This is the Direction your looking relative to the Up,
right, and location points and axis. NOTE you will hardly
ever have to change these values they are automatically
calculated.
LookAt: This is where the ViewPort will always point at you can change
the location, and the camera will always point to this 3D point
in space. NOTE you can disable auto view port calculations by
unchecking the Calculate LookAt checkbox.
Up: This is the up direction of the scene. This is automatically calculated
just like direction is.
Right: This is the direction right is at. By changing the x axis you
can compensate for the aspect ratio of the screen. However
this is done automatically.
Sky: This is the direction the sky is from the center of the view port.
OK Button: This accepts the changes and if the Calculate LookAt checkbox
is checked it will calculate Direction, Up, and Right axis's
based on the current location sky position, and look at point.
Cancel Button: Ignores all changes and doesn't calculate the new viewport
position.
Calculate LookAt: This enables if checked the auto calculation of
Direction, Up, and Right axis's. If not checked it doesn't
calculate these axis's.
Coordinate System: Above
+Y +Z Farther
| /
| /
|/
Left -X----0----X+ Right
/|
/ |
/ |
Closer -Z -Y
Below
Example: The Default view port looks forward from 100 units in front of
the center of the scene. About 1/2 unit down from the center
and 0 units to the left or right.
0 Center of the Universe
/
/
/
|-----/-| X = 0
| / | Y = -0.5
| | Z = -100
|-------|
Let's say we put a sphere at X = 0, Y = 0, Z = 0, and a light
at x = 0, y = 100, z = -110. wee would see the sphere right in
front of us about in the center of the screen. Now lets say
we wanted to look directly down on the sphere. All we have to do
is move our location to X = 0, Y = 100, Z = -0.0001 note we cannot
have the Y or Z values of the location ever = 0 or we will get
a floating point error, but the program will adjust the value to
1 if it detects a zero in either numbers. Now make sure LookAt
equals X = 0, Y = 0, and Z = 0, so we are looking at the sphere
at X = 0, Y = 0, Z = 0. Now trace the image you will now be looking
down on the sphere. Experiment with the location and Sky numbers
and see what interesting views you can come up with.