Miracle #03 16 июля 1999

Программирование

kodit Who's there? - Attribute bump mapping: bump mapping for those who have not entered.

    (C) Crite / Triumph

    (I) Blade / Triumph

    -----------------



    As once bored, I decided to write
lighting effect, the bulk surface
smarter to say bump mapping. Of course many of these effects 
have you seen in different demah, but my effect is more simple 
and fit into a frame, more precisely about

40,000 cycles.


    I have long thought by some light on the display screen and 
the flu has prompted me, finally turned out an attribute 
option:) As soon as a reservation that all lower contained 
nothing more than just a bump mapping'a algorithm and is 
designed to development of ideas novice coders.




           So my method is

           that you specify the volume
           CPC as a set of plates
           films with different angle of tilt
           at. That number plates

           taken in my source:


           4,3,2,1 - change the brightness

                     light;

           5,0 - no change.



    Here is how I define brightness
inclined plate. To do this I need
set the coordinates of the center and the current
pieces of the light beam. In theory this is done as follows: to 
remember the coordinates of the upper-left corner of the beam 
associated with the upper left corner of the screen, then add 
the numbers to determine the center this beam and compare the 
obtained values ​​with the coordinates of the current piece.



    All of this consumes a lot of time
and I went another way: Links
coordinate system with the upper-left corner,
but not the screen and light beam. Coordinates
center with respect to this coordinate system - constant, ie 
does not change number. Constant compared with the current

coordinate and, depending on the type of
the current site, call for different procedures (some of them 
below). Coordinate upper-left corner of the light beam relative 
to the upper-left corner of the screen I use only once in one 
step effect, to calculate the starting address in the 
attributes. 


    Procedure for calculating the brightness work like this: 
Take for example the plate 1, if it is located to the left than 
the center source, then we call this position # 1,

and if the right (ie, its light under a
angle closer to 90 degrees than in the
position # 1), called, respectively,
position # 2.


    Table Light is given the form of the beam
light, where the number of the color and radius
ring one of brightness. Brightness I did not
calculate the complex methods, and given two
Table TABL1 and TABL2 (for # 1 and # 2
position). Table Format: 1 - to
0th, 2 - for the first and so on up to 8
brightness.


    Coordinates are specified in a separate file. First is the 
coordinate of x, then y. But you should bear in mind that the 
beam light should not fly over the screen.

I did not do on this test, because
that it takes a long time. By the way
coordinates, you can set the program COORD (located in the 
appendix), it 100 sets of coordinates Lissajous figures.



    In order to know the speed of the program - remove the 
semicolon in the rows with "@". Source you will find in the 
appendix, it is called "LIGHT.H" (of course in a format 
ruleznogo assembler ALASM).




       That's all folx!