Solid5 1/8

 BBS: Inland Empire Archive
Date: 03-21-93 (03:40)             Number: 351
From: RICH GELDREICH               Refer#: NONE
  To: ALL                           Recvd: NO  
Subj: Solid5 1/8                     Conf: (2) Quik_Bas
Here's the solid 3-D program I've been talking about! Page 1 of 8.

'Page 1 of SOLID5.BAS begins here.
'Shaded 3-D animation with shadows [solid5.bas] for QB4.5/PDS
'By Rich Geldreich 1992
'   This version uses some floating  point math in the initialization
'code for shading, but after initialization floating point math is not
'used at all.
'   The  shading  imploys Lambert's Law to determine the intensity of
'each visible polygon.  Three simple  lookup tables are calculated at
'initialization time  which  are  used  to  eliminate  multiples  and
'divides in the main animation code.
'   The hidden face  detection  algorithm  was  made  by Dave Cooper.
'It's fast, and does not require any multiples and divides under most
'cases.  The "standard" way of detecting hidden faces, by finding the
'dot product of the normal of each polygon and  the  viewing  vector,
'was not just good (or fast) enough for me!
'   The PolyFill routine is the major  bottleneck  of  this  program.
'QB's  LINE  command isn't as fast as I would like it to be...  On my
'286-10, the speed isn't that bad (after all, this is all-QB!).  On a
'386 or 486, this thing should fly...  [hopefully]
'   The  shadows  are  calculated by projecting a line with the light
'source's vector through each of the points on the solid.  Where this
'line hits the ground  plane(which  has  a  constant Y coordinate) is
'where the new shadow point is plotted.
'   This program is 100% public domain- but  of  course  please  give
'some credit if you use anything from this program.  Thanks!
DECLARE SUB CullPolygons ()
DECLARE SUB DrawLine (xs%, ys%, xe%, ye%, EdgeList() AS ANY)
DECLARE SUB DrawObject ()
DECLARE SUB DrawShadows ()
DECLARE SUB EdgeFill (EdgeList() AS ANY, YLow%, YHigh%, C%)
DECLARE SUB FindNormals ()
DECLARE SUB PolyFill (x1%, y1%, x2%, y2%, x3%, y3%, C%)
DECLARE SUB RotatePoints ()
DECLARE SUB ShadePolygons ()

CONST True = -1, False = 0

TYPE EdgeType              'for fast polygon rasterization
    Low         AS INTEGER
    High        AS INTEGER
TYPE PointType
    XObject     AS INTEGER 'original cooridinate
    YObject     AS INTEGER
    ZObject     AS INTEGER 'rotated coodinated
    XWorld      AS INTEGER
    YWorld      AS INTEGER
    ZWorld      AS INTEGER
    XView       AS INTEGER 'rotated & translated coordinate
    YView       AS INTEGER
    XShadow     AS INTEGER 'coordinates projected onto the ground plane
    YShadow     AS INTEGER
TYPE PolyType
    P1          AS INTEGER '3 points which make up the polygon(they _
    P2          AS INTEGER ' to the point list array)
    P3          AS INTEGER
    Culled      AS INTEGER 'True if plane not visible
    ZCenter     AS INTEGER 'Z center of polygon
    ZOrder      AS INTEGER 'Used in the shell sort of the ZCenters
    Intensity   AS INTEGER 'Intensity of polygon
    WorldXN     AS INTEGER 'Contains the coordinates of the point
    WorldYN     AS INTEGER ' which is both perpendicular and a constant
    WorldZN     AS INTEGER ' distance from the polygon
    NormalX     AS INTEGER 'Normal of polygon -128 to 128
    NormalY     AS INTEGER ' (used for fast Lambert shading)
    NormalZ     AS INTEGER
TYPE LineType
    P1          AS INTEGER 'Used for shadow projection
    P2          AS INTEGER

DIM SHARED EdgeList(199) AS EdgeType
DIM SHARED SineTable(359 + 90) AS LONG 'cos(x)=sin(x+90)
DIM SHARED R1, R2, R3, ox, oy, oz
DIM SHARED MaxPoints, MaxPolys, MaxLines

DIM SHARED lines(100) AS LineType
DIM SHARED Polys(100) AS PolyType
DIM SHARED Points(100) AS PointType
DIM SHARED lx(256), ly(256), lz(256)   'lookup tables for Lambert _
DIM SHARED s, XLow(1), XHigh(1), YLow(1), YHigh(1)
DIM SHARED ShadowXLow(1), ShadowXHigh(1), ShadowYLow(1), ShadowYHigh(1)
DIM SHARED lx, ly, lz

PRINT "QuickBASIC/PDS 3-D Solid Animation": PRINT "By Rich Geldreich _
PRINT : PRINT "Keys: [Turn NUMLOCK on]"
PRINT "Left.....................Angle 1 -"
'Continued on page 2

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