Define Bitmap Alien Animations.
Define Bitmap Alien Animations
This document assumes that you have read and understood the 'HOW2-Define_Aliens' document
and that you have got as far as selecting the
[ DEFINE ANIMATION FRAMES ]
option from the alien statistics screen.
You will see a list of all the animations which an alien will perform.
NB: The diagonal views (Front-left, Front-right, Back-left and Back-right) are NOT IMPLEMENTED
in the current version, so don't bother drawing or defining animations of aliens in those
All the animations have the same format, but their usage varies as follows:
The 'movement' animations refer to the various directions it is possible to see the alien
from as it walks/flies around. These animations are played looped, ie when the last frame is
reached, animation continues from the first frame.
NB: It is VERY important that all the direction animations have the same number of frames.
This is because, to improve continuity, the program DOES NOT reset the animation when
your view of an alien changes. In other words, if it reaches frame 5 whilst walking
away from you, then turns left, it will start from frame 5 as it walks left.
The other, 'action' animations are one-shot anims played when the specified action occurs.
DEFINING AN ANIMATION SEQUENCE
Click on the animation sequence you wish to define.
You will see a complicated looking line of values at the top, and buttons for adding a new
frame to the end of the list and deleting the last in the list. As for objects and bullets,
when a new frame is added, it takes on the values of its predecessor, so set up invariants,
for example which graphic file the frames are from, before adding frames.
The values, from left to right, are:
0-19 Frame number
GF: Graphic File. This is the number of the file the frame is to come from. Click on the
value and then on the name of the file you have previously loaded.
FN: Frame number. This is the actual frame within the graphic file which will be drawn.
an 'R' in front of the number indicates the frame will be flipped horizontally before
drawing on-screen. This is handy as you can have one set of frames for left AND right
movement, with the computer flipping them as needed.
SW: Scaled Width. This is the width to which the frame will be scaled (Not including the
effects of distance). Must be 255 or less. Click to change.
SH: Scaled Height. This is the height to which the frame will be scaled (Not including the
effects of distance). Must be 255 or less. Click to change
VO: Vertical offset. Normally the frame is drawn centred on the alien's positon, however with
this value you can offset each frame vertically by a set amount, perhaps to make it
appear to bob up and down. Click to change.
FX: This is the number of the sound effect which will be played whenever the alien reaches
this frame of animation. Click on the number to get a list of currently loaded sound
effects, and click on an effect OR at the top of the screen for no effect. With this
you can easily synchronise footstep sounds with the correct frames of animation on-screen,
or shooting effects with the precise frame the gun appears to fire!
AC: Action Star. Clicking next to this toggles on and off an 'action star'. If an action
star is present, the alien will perform an action, such as moving or shooting. The precise
nature of the action is dependant upon which animation sequence you are defining. Using
the action stars you can make an alien walk slowly by having a sequence like this:
0 GF: 1 FN: 1 . . . . . . . . . . . . . . . AC: *
1 GF: 1 FN: 1 . . . . . . . . . . . . . . . AC:
2 GF: 1 FN: 1 . . . . . . . . . . . . . . . AC:
3 GF: 1 FN: 1 . . . . . . . . . . . . . . . AC:
4 GF: 1 FN: 2 . . . . . . . . . . . . . . . AC: *
5 GF: 1 FN: 2 . . . . . . . . . . . . . . . AC:
6 GF: 1 FN: 2 . . . . . . . . . . . . . . . AC:
7 GF: 1 FN: 2 . . . . . . . . . . . . . . . AC:
Assuming frames 1 and 2 are part of a walking sequence, the above would instruct the
computer to display each frame for 4 time units, and only move the alien in the first
of the four time units, thus preventing the alien 'moonwalking' between frames.
You can make an alien fire a specific number of times by including several repetitions
of the shooting animation, with an Action Star next to the appropriate frame in each
AI: Animation Instruction. Usually, this contains a downward arrow 'v', indicating that the
animation will proceed to the next frame in sequence (or to the first if the last one is
reached). However, it is sometimes very useful to be able to repeat a certain sequence
a set number of times, or perhaps even a random number of times. There are therefore
another 3 Animation Instructions:
S X Store number X in counter.
R X Add a random number between 0 and X to the counter
D X Subtract 1 from the counter, and jump to frame X if the result was NOT zero.
Hence you could make an alien howl, then take a random number of steps between
10 and 20 before howling again, like this:
0 GF: 1 FN: 5 . . . . . . . . . . . FX: 3 AC: AI S10
1 GF: 1 FN: 5 . . . . . . . . . . . FX: 0 AC: AI R10
2 GF: 1 FN: 1 . . . . . . . . . . . FX: 0 AC: * AI v
* WALKING ANIMATION
9 GF: 1 FN: 4 . . . . . . . . . . . FX: 0 AC: * AI D 2
Click and follow the instructions to change the AI value of a frame.
AUX: Auxilliary object frame number. This selects a frame defined in the auxilliary object
for that alien to be displayed over the top of the alien. Click on the value and you
will be shown the animation sequence you defined for the auxilliary object. Simply click
on the appropriate frame OR at the top of the screen for no frame.
XO: Auxilliary object X Offset. The amount by which the centre of the auxilliary object is
offset from the centre of the alien graphic. Useful for gun barrel flashes, so you
can make gun flashes appear over the top of the gun they appear from, wherever the gun
YO: Auxilliary object Y Offset. As above, but vertically rather than horizontally.
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