* #8DDE - x=N y=R
* #8E34 - x=R y=R
The bug that delete background near the left border of the screen is caused by star shield routine at #0ED9.
If you want to try to use theses informations, beware in some version some code is not located in the same place.Theses informations have been taken from the Aldo Reset version and the original dump.
[[User:Fano|Fano]] 09:58, 19 November 2009 (UTC)
In Nicholas CAMPBELL and CNG versions, code seems to be offseted to -14 bytes.
In original code, the subprogram that load levels is located at #5B64.It gets level number at #719C ,compute track number track=((lvl-#30)*4)+8 and download the 3 tracks (#3600 bytes) at #C4AE so levels are located at track 8,12,16,20,24,28,32 and to finish it calls #8F2A to do loading.
[[User:Fano|Fano]] 13:08, 20 November 2009 (UTC)
== Objets/Sprites subsytem ==
The routines used to put sprites/objects to the rendering system (#8D08,#8D70,#8DDE,#8E34) take the following parameters :
*HL sprite graphics address
*D,E sprite dimension in char units (height,width)
*B,C sprite position in char units (y,x)
Sprite graphics are composed of theses structures:
*BYTE : attribute
*BYTE*8 : 1bit graphics , only present if attribute <> #36
Attribute seems to be only used to compute color, only the 2 lower bits are used like this :
* 10 (2) : color 1
* 11 (3) : color 3
* 00 (0) or 01 (1) : color 2
There are 2 routines to solve sprite dimensions and adress from a sprite number in A : #8E97 for basic sprites (héro,modules,weapons,logo,etc...) and #8E90 for levels sprites.Theses routines return pixels address in HL and dimensions in char units in D,E.
Sprites tables are composed of theses structures :
*BYTE width in char units
*BYTE height in char units
*WORD pixels address
The basic sprites table if located at #BC67 and level sprites table address can be found at (#C4BA)
Here is some example code written in Basic to convert R-Type sprites from uncompressed 64K type 1 SNA to BMP format :[[file:R_extractspr.x]]
Example :
[[File:Spr_40.png]]
(Violet chars are marked as #36 so they are ignored)
[[User:Fano|Fano]] 16:47, 21 November 2009 (UTC)
==Level graphics==
Let's continue for 2K10 !
Game screen is composed of 8*5 blocks of 4*4 chars (8*8 pixies).Blocks are stored in memory in the same way as sprites except char pixies are always presents.
Per char :
*BYTE : flags, defines color, bit 7 defines if char is solid.
*BYTE*8 : 1bit graphics
There are 16 chars so 144 bytes per block.
Levels are composed of columns of 5 blocks.The first column of the level is located at #C4B1 (byte).The column number 0 is located at (#C4BC)
A column address (word) can be computed like this : (column*5) + (#C4BC)
Each byte of the column is a block number :
* bit 7 -> set if verticaly reversed
* bit 6 -> set if horizontaly reversed
* bits 0->5 block index
Using block index , it is possible to compute address (word) with this simple formula :
(#C4BC)-((index+1)*144)
Routine at #167B solves block index in A and return block address in HL.
Code located at #5C4F draws the first screen of the level before scrolling.It uses the sprite code (#8D08,#8D70,#8DDE,#8E34) to put the level graphics on screen.
Current column is located at #7A84 and there is a copy of (#C4BC) at #C4AE.When game passes a checkpoint , it saves the current column at #C4AE so when player dies, game restarts at #C4AE.
Code located at #8A7F feeds scrolling , update attribute array , draw blocks on right side of the screen.There are 4 routines to feed scroll according to reverse flags.
* #1E4C - x=N y=N
* #1E83 - x=R y=N
* #1EC3 - x=N y=R
* #1640 - x=R y=R
[[User:Fano|Fano]] 20:23, 6 January 2010 (UTC)