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Amiga ACS 1998 #6
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amigaacscoverdisc1998-061998.iso
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descent
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texmap
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tmap_z.asm
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Assembly Source File
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1998-06-08
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4KB
|
167 lines
;THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
;SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
;END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
;ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
;IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
;SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
;FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
;CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
;AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
;COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
;
; $Source: f:/miner/source/texmap/rcs/tmap_z.asm $
; $Revision: 1.4 $
; $Author: mike $
; $Date: 1994/11/30 00:57:06 $
;
; Assembly routines to do a flat-shaded z-buffer tmap.
;
; $Log: tmap_z.asm $
; Revision 1.4 1994/11/30 00:57:06 mike
; optimization.
;
; Revision 1.3 1994/11/12 16:41:14 mike
; jae -> ja.
;
; Revision 1.2 1994/07/08 17:43:14 john
; Added flat-shaded-zbuffered polygon.
;
; Revision 1.1 1994/07/08 10:58:18 john
; Initial revision
;
;
.386
public asm_tmap_scanline_flat_z_
public _tmap_flat_color_z
public _tmap_z_buffer
include tmap_inc.asm
_DATA SEGMENT DWORD PUBLIC USE32 'DATA'
extrn _fx_y:dword
extrn _fx_xleft:dword
extrn _fx_xright:dword
extrn _fx_z:dword
extrn _fx_dz_dx:dword
;** extrn _pixptr:dword
_tmap_flat_color_z db ?
_tmap_z_buffer dd 0
_loop_count dd 0
_DATA ENDS
DGROUP GROUP _DATA
_TEXT SEGMENT PARA PUBLIC USE32 'CODE'
ASSUME DS:_DATA
ASSUME CS:_TEXT
; --------------------------------------------------------------------------------------------------
; Enter:
; _xleft fixed point left x coordinate
; _xright fixed point right x coordinate
; _y fixed point y coordinate
;**; _pixptr address of source pixel map
; for (x = (int) xleft; x <= (int) xright; x++) {
; _setcolor(read_pixel_from_tmap(srcb,((int) (u/z)) & 63,((int) (v/z)) & 63));
; _setpixel(x,y);
;
; z += dz_dx;
; }
asm_tmap_scanline_flat_z_:
pusha
; Setup for loop: _loop_count iterations = (int) xright - (int) xleft
;**; esi source pixel pointer = pixptr
; edi initial row pointer = y*320+x
; set esi = pointer to start of texture map data
;** mov esi,_pixptr
; set edi = address of first pixel to modify
mov edi,_fx_y
shr edi,16
cmp edi,_window_bottom
ja _none_to_do
imul edi,_bytes_per_row
mov eax,_fx_xleft
sar eax,16
jns eax_ok
sub eax,eax
eax_ok:
add edi,eax
mov esi,edi
shl esi, 2
add esi, _tmap_z_buffer
add edi,write_buffer
; set _loop_count = # of iterations
mov eax,_fx_xright
sar eax,16
cmp eax,_window_right
jb eax_ok1
mov eax,_window_right
eax_ok1: cmp eax,_window_left
ja eax_ok2
mov eax,_window_left
eax_ok2:
mov ebx,_fx_xleft
sar ebx,16
sub eax,ebx
js _none_to_do
cmp eax,_window_width
jbe _ok_to_do
mov eax,_window_width
_ok_to_do:
mov _loop_count, eax
mov cl,_tmap_flat_color_z
mov edx, _fx_z
mov ebp, _fx_dz_dx
mov ebx, 4
_size = (_end1 - _start1)/num_iters
mov eax,num_iters-1
sub eax,_loop_count
jns j_eax_ok1
inc eax ; sort of a hack, but we can get -1 here and want to be graceful
jns j_eax_ok1 ; if we jump, we had -1, which is kind of ok, if not, we int 3
int 3 ; oops, going to jump behind _start1, very bad...
sub eax,eax ; ok to continue
j_eax_ok1: imul eax,eax,dword ptr _size
add eax,offset _start1
jmp eax
align 4
_start1:
rept num_iters
local l1
cmp edx, [esi]
jge l1
mov [esi], edx
mov [edi], cl
l1: add esi, ebx
add edx, ebp
inc edi
endm
_end1:
_none_to_do: popa
ret
_TEXT ends
end