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DenTut15-Pas
There is a discussion going on in Usenet, mostly saying that trainers etc. should be written a bit more formally and none of this gay banter and familiar language should be used. My "quotes" would definately be out
But, until I get paid for doing this (and there don't seem to be any takers
on that score), I will continue to write in this manner. My apologies to those
who dont like this, but hey, its free, what did you expect?
This trainer is on plasmas, and the sample program actually became quite large, mostly due to the fact that there was some plasma stuff I wanted to try out.
The concept is very simple, at least for this plasma, so you shouldn't have any problems understanding it ... AFTER you have read the text file ... jumping straight into the source may be hazardous to your brain.
Plasmas are a great way to wow your friends by their wierd shapes and forms. I was at one stage going to write a game where the bad guy just had two circular plasmas instead of eyes... I am sure you will find creative and inventive new ways of doing and using plasmas.
When you get right down to it, this method of realtime plasmas is merely an intersection of four COS waves. We get our color at a particular point by saying :
The trick is getting the four indexes of that cos table array to create something that looks nice. This is how we organise it : Have two of them being indexes for vertical movement and two of them being indexes for horizontal movement.
This means that by changing these values we can move along the plasma. To draw an individual screen, we pass the values of the four to another four so that we do not disturb the origional values. For every pixel across, we add values to the first two indexes, then display the next pixel. For every row down, we add values to the second two indexes. Sound complex enough? Good, because that what we want, a complex shape on the screen.
By altering the origional four values, we can get all sorts of cool movement and cycling of the plasma. The reason we use a cos table is as follows : a cos table has a nice curve in the value of the numbers ... when you put two or more together, it is possible to get circular pictures ... circles are hard to do on a computer, so this makes it a lot easier...
Okay, now you can have a look at the source file, all I do is put the above into practice. I did add one or two things though ...
Background : This is just a large array, with the values in the array being added to the plasma at that pixel.
Psychadelic : This cycles through about 7000 colors instead of just rotating through the base 256.
Here is how we do a step-crossfade.
Each r,g,b value can be between 0 and 64. Have the pallette we want to get to in bob and the temporary pallette in bob2. For each step, from 0 to 63 do the following :
move color 0 into temp
move color 1 into color 0 move color 2 into color 1 move color 3 into color 2 and so on till color 255
move temp into color 255
And you pallette is rotating. Easy huh? Recheck tut 2 for more info on pallette rotation
As always, I am on the lookout for more ideas for future tuts, if you have some, mail me!
No quote today, this lan doesn't encourage creative thinking ;) However, there will be quotes in future as I have been told that some people like them. Even Pipsy said this while we were playing Ctrl-Alt-Del (two player game, one has to hit ctrl and alt as the other hits del, and the person hitting the del has to do it quickly so that the computer doesnt reboot. If the computer reboots the person who was hitting ctrl and alt has won. I thought I was doing really badly against Pipsy until I found out that the computer had frozen)
Byeeee.... - Denthor 14:11 16-9-94
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DenTut15-Pas
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³ W E L C O M E ³
³ To the VGA Trainer Program ³ ³
³ By ³ ³
³ DENTHOR of ASPHYXIA ³ ³ ³
ÔÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ; ³ ³
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
--==[ PART 15 ]==--
- Introduction
There is a discussion going on in Usenet, mostly saying that trainers etc. should be written a bit more formally and none of this gay banter and familiar language should be used. My "quotes" would definately be out
But, until I get paid for doing this (and there don't seem to be any takers
on that score), I will continue to write in this manner. My apologies to those
who dont like this, but hey, its free, what did you expect?This trainer is on plasmas, and the sample program actually became quite large, mostly due to the fact that there was some plasma stuff I wanted to try out.
The concept is very simple, at least for this plasma, so you shouldn't have any problems understanding it ... AFTER you have read the text file ... jumping straight into the source may be hazardous to your brain.
Plasmas are a great way to wow your friends by their wierd shapes and forms. I was at one stage going to write a game where the bad guy just had two circular plasmas instead of eyes... I am sure you will find creative and inventive new ways of doing and using plasmas.
- How do plasmas work?
When you get right down to it, this method of realtime plasmas is merely an intersection of four COS waves. We get our color at a particular point by saying :
col := costbl[one]+costbl[two]+costbl[three]+costbl[four];
The trick is getting the four indexes of that cos table array to create something that looks nice. This is how we organise it : Have two of them being indexes for vertical movement and two of them being indexes for horizontal movement.
This means that by changing these values we can move along the plasma. To draw an individual screen, we pass the values of the four to another four so that we do not disturb the origional values. For every pixel across, we add values to the first two indexes, then display the next pixel. For every row down, we add values to the second two indexes. Sound complex enough? Good, because that what we want, a complex shape on the screen.
By altering the origional four values, we can get all sorts of cool movement and cycling of the plasma. The reason we use a cos table is as follows : a cos table has a nice curve in the value of the numbers ... when you put two or more together, it is possible to get circular pictures ... circles are hard to do on a computer, so this makes it a lot easier...
Okay, now you can have a look at the source file, all I do is put the above into practice. I did add one or two things though ...
Background : This is just a large array, with the values in the array being added to the plasma at that pixel.
Psychadelic : This cycles through about 7000 colors instead of just rotating through the base 256.
- Clever fading
Here is how we do a step-crossfade.
Each r,g,b value can be between 0 and 64. Have the pallette we want to get to in bob and the temporary pallette in bob2. For each step, from 0 to 63 do the following :
bob2[loop1].r:=bob[loop1].r*step/64;
That means if we are halfway through the crossfade (step=32) and the red
value is meant to get to 16, our equation looks like this :
r:=16*32/64
r=8
Which is half of the way to where it wants to be. This means all colors will
fade in/out with the same ratios... and look nicer.- Rotating the pallette
move color 0 into temp
move color 1 into color 0 move color 2 into color 1 move color 3 into color 2 and so on till color 255
move temp into color 255
And you pallette is rotating. Easy huh? Recheck tut 2 for more info on pallette rotation
- In closing
As always, I am on the lookout for more ideas for future tuts, if you have some, mail me!
No quote today, this lan doesn't encourage creative thinking ;) However, there will be quotes in future as I have been told that some people like them. Even Pipsy said this while we were playing Ctrl-Alt-Del (two player game, one has to hit ctrl and alt as the other hits del, and the person hitting the del has to do it quickly so that the computer doesnt reboot. If the computer reboots the person who was hitting ctrl and alt has won. I thought I was doing really badly against Pipsy until I found out that the computer had frozen
)Byeeee.... - Denthor 14:11 16-9-94
[Edit this page] [Page history] [What links here] [Discuss this topic] [Printer Friendly]
