TweetFollow Us on Twitter

Jul 97 Challenge

Volume Number: 13 (1997)
Issue Number: 7
Column Tag: Programmer's Challenge

Jul 97 - Programmer's Challenge

by Bob Boonstra, Westford, MA

Disambiguator

The Challenge this month is to write a string completion routine loosely patterned after the keyword lookup facility in the QuickView utility. QuickView will suggest a completion of the keyword as you begin to type it, and update that suggested completion as you continue to type. In the Toolbox Assistant, for example, if you are looking for documentation on InitGraf and type "i", the suggested completion is "iconIDToRgn". As you continue by typing "n", the suggestion becomes "index2Color". Adding "i" yields "initAllPacks"; adding "t" leaves the suggestion intact; adding "g" changes it to "initGDevice". Finally, typing "r" gives the desired "initgraf".

For our disambiguator, you will be given an unsorted list of words and an opportunity to preprocess them. Then you will be given a string to match and asked to return a list of words matching findString. To make the problem more interesting, the match string can contain wild card characters, as described below.

The prototype for the code you should write is:

typedef unsigned long ulong;

void InitDisambiguator(
   const char *const wordList[],   /* words to match against */
   ulong numWords,                 /* number of words in wordList */
   void *privStorage,              /* private storage preinitialized to zero */
   ulong storageSize               /* number of bytes of privStorage */
);

ulong /*numMatch*/ Disambiguator(
   const char *const wordList[],   /* words to match against */
   ulong numWords,                 /* number of words in wordList */
   void *privStorage,              /* private storage */
   ulong storageSize,              /* number of bytes of privStorage */
   char *findString,               /* string to match, includes wild cards */
   char *matchList[]               /* return matched words here */
);

Your InitDisambiguator routine will be called with an unsorted list wordList of numWords null-terminated words to match. The wordList words will include alphanumeric characters, spaces, and underscores. You will also be provided with a pointer privStorage to storageSize bytes of preallocated memory initialized to zero. The amount of storage provided will be at least 20 bytes for each word in wordList, plus one byte for each character in the wordList (including the null byte, and rounded up to a multiple of 4). In other words, storageSize will be no smaller than minStorage, calculated as:

for (minStorage=0,i=0; i<numWords; i++)
   minStorage += 20 + 4*(1+strlen(wordList[i])/4);

InitDisambiguator is not allowed to modify the wordList, but you may store a sorted version of wordList, or pointers to the words in sorted order, in privStorage. The first four parameters provided to Disambiguator will be identical as those provided to InitDisambiguator. In addition, you will be provided with the null-terminated findString and a preallocated array matchList with numWords entries where you are to store pointers to the words that match findString. Your string matches should be case insensitive (i.e., "initgr" matches "InitGraf". The matchList should be returned with the strings ordered in case-insensitive ASCII order (i.e., space < [0..9] < [A-Za-z] < underscore).

The findString may also contain zero or more of the wildcard characters '?', '*', and '+'. The wildcard '?' matches any single character, '*' matches zero or more characters, and '+' matches one or more characters. So, for example, "*graf" matches any string ending in the (case-insensitive) string "graf", while "+1Ind+" matches any string containing "1Ind" between the first and last characters of a word.

For each call to InitDisambiguator, your Disambiguator routine will be called an average of 100 to 1000 times. The winner will be the solution that finds the correct matchList in the minimum amount of time, including the time taken by the initialization routine.

This will be a native PowerPC Challenge, using the latest CodeWarrior environment. Solutions may be coded in C, C++, or Pascal. The problem is based on a suggestion by Charles Kefauver, who pointed me to an April, 1995, AppleDirections article discussing the user interface for a disambiguator. Charles wins 2 Challenge points for his suggestion.

Three Months Ago Winner

Congratulations to ACC Murphy (Perth, Australia), for submitting the faster (and smaller) of the two entries I received for the Projection Challenge. This problem required contestants to calculate the image of a set of input polygons, including the shadows cast by one polygon on another, given an observation viewpoint and an illumination point.

Both of the submitted solutions used a ray-tracing technique. The winning solution calculates, for each point on the projection plane, the nearest polygon to the viewpoint among those intersecting the ray from the plane to the viewpoint. It then does another ray-trace to determine if there are any other polygons between the illumination point and the projected polygon, identifying the point as being in shadow if an intervening polygon is found.

I ran three test cases, moving the polygons 10 times for a given viewpoint in each case, using a GWorld bounds rectangle slightly smaller than my 1024x768 monitor. As you can see from the execution times, considerable refinement would be needed before this code could be used for animation.

A good discussion of the projection and hidden surface removal algorithms applicable to this problem can be found in the Black Art of Macintosh Game Programming, by Kevin Tieskoetter. In addition to discussing the z-buffer ray-tracing algorithm, it describes another technique for hidden surface removal called the Painter's algorithm. This approach breaks the polygons to be displayed into pieces such that each piece is entirely in front of or entirely behind any other piece, as seen from the viewpoint. The polygons can then be sorted and displayed without looking at each pixel in the image. For our application, two polygon decompositions would be required, one for the image, and one for the shadows.

The table below lists, for each entry, the execution time for each case and the code size. The number in parentheses after the entrant's name is the total number of Challenge points earned in all Challenges to date prior to this one.

                      Case 1   Case 2   Case 3    Total       Code
Name                   Time     Time     Time   Time (secs)   Size
A.C.C. Murphy (10)    29.02    23.64    81.61     134.27      4196
Ernst Munter (232)    20.87    58.11    89.76     168.74      7192

Top 20 Contestants

Here are the Top Contestants for the Programmer's Challenge. The numbers below include points awarded over the 24 most recent contests, including points earned by this month's entrants.

Rank    Name             Points   Rank     Name             Points
   1.   Munter, Ernst      194       11.   Beith, Gary         24
   2.   Gregg, Xan         114       12.   Cutts, Kevin        21
   3.   Cooper, Greg        54       13.   Nicolle, Ludovic    21
   4.   Larsson, Gustav     47       14.   Picao, Miguel Cruz  21
   5.   Lengyel, Eric       40       15.   Brown, Jorg         20
   6.   Boring, Randy       37       16.   Gundrum, Eric       20
   7.   Mallett, Jeff       37       17.   Higgins, Charles    20
   8.   Lewis, Peter        32       18.   Kasparian, Raffi    20
   9.   Murphy, ACC         30       19.   Slezak, Ken         20
   10.  Antoniewicz, Andy   24       20.   Studer, Thomas      20

There are three ways to earn points: (1) scoring in the top 5 of any Challenge, (2) being the first person to find a bug in a published winning solution or, (3) being the first person to suggest a Challenge that I use. The points you can win are:

1st place   20 points             5th place   2 points
2nd place   10 points           finding bug   2 points
3rd place   7 points   suggesting Challenge   2 points
4th place   4 points

Here is A.C.C. Murphy's winning solution:
Challenge.p
A.C.C. Murphy

unit Challenge;

(*

Assumptions:
   Storage space must be big enough for 13 floats per polygon
   All points must be significantly smaller in magnitude than BIG_FLOAT = 
      1000000.0
   Polygons are translucent (their colour based uplon lighting is independent 
      of the side of the polygon that is lit)
   50% attenuation of colour is used
   50% attenuation of black is black
      
Method:
   InitProjection is not used
   
   First we precalculate a small bounding sphere for the polygon points.
   Next we get the information about the GWorld to allow direct pixel access.
   Then for each point on the GWorld, we trace the ray from the point to the 
      eye, intersecting it with each polygon and finding the one closes to 
      the eye (furthest forward, since the eye is infront of all polygons).  
      That determines the colour.  We then trace the ray from that intersection 
      point to the light source to determine whether the point is in shadow, 
      and if so we halve the intensity. We set the colour of the pixel and 
      move on.
   
   Optimizations:
      Direct pixel access to the GWorld (known to be 32 bit)
      Bounding sphere used to optimize the ray/polygon intersection test.
      Time is approximately 2 microseconds per pixel per polygon on an 8500.
*)

interface

   uses
      Types, Quickdraw, QDOffscreen;
      
   const
      kMAXPOINTS = 10;

   const
      BIG_FLOAT = 1000000.0;
         
   type
      float = real;
      
   type
      My2DPoint = record (* point in z==0 plane*)
         x2D: float; (* x coordinate*)
         y2D: float; (* y coordinate*)
      end;
      My3DPoint = record
         x3D: float;                 (* x coordinate*)
         y3D: float;                 (* y coordinate*)
         z3D: float;                 (* z coordinate*)
      end;
      My3DDirection = record
         thetaX:float;              (* angle in radians*)
         thetaY:float;              (* angle in radians*)
         thetaZ:float;              (* angle in radians*)
      end;
      MyPlane = record
         planeNormal: My3DDirection; (* normal vector to plane*)
         planeOrigin: My3DPoint;     (* origin of plane in 3D space*)
      end;
      MyPolygon = record
         numPoints: longint;      (* number of points in polygon*)
         thePoint: array[0..kMAXPOINTS-1] of My2DPoint;
                                  (* polygon in z==0 plane*)
         polyPlane: MyPlane;      (* rotate/translate z==0 plane to this plane*)
         polyColor: RGBColor;     (* the color to draw this polygon*)
      end;
      MyPolygonArray = array[0..0] of MyPolygon;
      
         
   procedure InitProjection(
      const viewPoint: My3DPoint;(* viewpoint from which to project*)
      const illumPoint:My3DPoint;(* viewpoint from which to draw shadow*)
      storage: univ Ptr;         (* auxiliary storage preallocated for your use*)
      storageSize: longint       (* number of bytes of storage*)
   );

   procedure CalcProjection(
      offScreen: GWorldPtr;          (* GWorld to draw projection *)
      const thePolys: MyPolygonArray;(* polygons to project *)
      numPolys: longint;             (* number of polygons to project *)
      const viewPoint: My3DPoint;    (* viewpoint from which to project *)
      const illumPoint: My3DPoint;
                               (* illumination point from which to draw shadow *)
      storage: univ Ptr;       (* auxiliary storage preallocated for your use*)
      storageSize: longint     (* number of bytes of storage*)
   );

implementation

   type
      Ray3D = record
         origin: My3DPoint;
         direction: My3DPoint;
      end;
      PolygonExtra = record
         normal, rotX, rotY, center: My3DPoint;
         radius2: float;
      end;
      PolygonExtraArray = array[0..0] of PolygonExtra;
      StorageRecord = record
         poly_extra: PolygonExtraArray;
                  { must be at the end, since it's an extensible array }
      end;
      StorageRecordPtr = ^StorageRecord;
      
   function DotProduct(const src1, src2 : My3DPoint) : float;
   begin
      DotProduct := src1.x3D*src2.x3D +  
                    src1.y3D*src2.y3D +  
                    src1.z3D*src2.z3D;
   end;
   
CrossProduct
   procedure CrossProduct(src1, src2 : My3DPoint; 
                    var dst : My3DPoint);
   begin
      dst.x3D := src1.y3D*src2.z3D - src1.z3D*src2.y3D;
      dst.y3D := src1.z3D*src2.x3D - src1.x3D*src2.z3D;
      dst.z3D := src1.x3D*src2.y3D - src1.y3D*src2.x3D;
   end;
   
AddVectors
   procedure AddVectors(const src1, src2 : My3DPoint; 
                     var dst : My3DPoint);
   begin
      dst.x3D := src1.x3D + src2.x3D;
      dst.y3D := src1.y3D + src2.y3D;
      dst.z3D := src1.z3D + src2.z3D;
   end;
      
SubtractVectors
   procedure SubtractVectors(const src1, src2 : My3DPoint; 
                      var dst : My3DPoint);
   begin
      dst.x3D := src1.x3D - src2.x3D;
      dst.y3D := src1.y3D - src2.y3D;
      dst.z3D := src1.z3D - src2.z3D;
   end;
   
MidPoint
   procedure MidPoint( const src1, src2 : My3DPoint; 
                      var dst : My3DPoint);
   begin
      dst.x3D := (src1.x3D + src2.x3D) / 2;
      dst.y3D := (src1.y3D + src2.y3D) / 2;
      dst.z3D := (src1.z3D + src2.z3D) / 2;
   end;
   
Distance2
   function Distance2( const src1, src2 : My3DPoint) : float;
   begin
      Distance2 := sqr(src1.x3D - src2.x3D) + 
                      sqr(src1.y3D - src2.y3D) + 
                      sqr(src1.z3D - src2.z3D);
   end;
   
ScaleVector
   procedure ScaleVector(const src : My3DPoint; scale : float; 
                      var dst : My3DPoint);
   begin
      dst.x3D := src.x3D * scale;
      dst.y3D := src.y3D * scale;
      dst.z3D := src.z3D * scale;
   end;
      
NormalizeVector
   procedure NormalizeVector(const src : My3DPoint;
                      var dst : My3DPoint);
      var
         length : float;
   begin
      length := sqrt(DotProduct(src,src));   
      dst.x3D := src.x3D / length;
      dst.y3D := src.y3D / length;
      dst.z3D := src.z3D / length;
   end;
   
MakeViewRay
   procedure MakeViewRay(const eye : My3DPoint;
                      x, y, z: float; var ray : Ray3D);
   begin
      ray.origin.x3D := x;
      ray.origin.y3D := y;
      ray.origin.z3D := z;
      ray.direction.x3D := eye.x3D - x;
      ray.direction.y3D := eye.y3D - y;
      ray.direction.z3D := eye.z3D - z;
      NormalizeVector(ray.direction, ray.direction);
   end;
   
RotateX
   procedure RotateX(src : My3DPoint; sinA, cosA : float; 
                      var dst : My3DPoint);
   begin
      dst.x3D := src.x3D;
      dst.y3D := cosA*src.y3D - sinA*src.z3D;
      dst.z3D := sinA*src.y3D + cosA*src.z3D;
   end;
   
RotateY
   procedure RotateY( src : My3DPoint; sinA, cosA : float; 
                      var dst : My3DPoint);
   begin
      dst.x3D := cosA*src.x3D + sinA*src.z3D;
      dst.y3D := src.y3D;
      dst.z3D := -sinA*src.x3D + cosA*src.z3D;
   end;
   
RotateZ
   procedure RotateZ( src : My3DPoint; sinA, cosA : float; 
                      var dst : My3DPoint);
   begin
      dst.x3D := cosA*src.x3D - sinA*src.y3D;
      dst.y3D := sinA*src.x3D + cosA*src.y3D;
      dst.z3D := src.z3D;
   end;
   
PointInPlaneInPolygon
   function PointInPlaneInPolygon( const pt: My2DPoint; const 
               poly: MyPolygon ): boolean;
      function Quadrant( const pt: My2DPoint; x, y: float ): 
                      longint;
      begin
         if pt.x2D > x then begin
            if pt.y2D > y then begin
               Quadrant := 0;
            end else begin
               Quadrant := 3;
            end;
         end else begin
            if pt.y2D > y then begin
               Quadrant := 1;
            end else begin
               Quadrant := 2;
            end;
         end;
      end;
      
      function x_intercept( const pt1, pt2: My2DPoint;
                      yy: float ): 
                      float;
      begin
         x_intercept := pt2.x2D - 
                     ( (pt2.y2D - yy) * 
                        ((pt1.x2D - pt2.x2D)/(pt1.y2D - pt2.y2D)) );
      end;
      
      var
         i, angle, quad, next_quad, delta: longint;
         last_vertex, next_vertex: My2DPoint;
   begin
      angle := 0;
      last_vertex := poly.thePoint[poly.numPoints-1];
      quad := Quadrant( last_vertex, pt.x2D, pt.y2D );
      for i := 1 to poly.numPoints do begin
         next_vertex := poly.thePoint[i-1];
         next_quad := Quadrant( next_vertex, pt.x2D, pt.y2D );
         delta := next_quad - quad;
         case delta of
            3: delta := -1;
            -3: delta := 1;
            2, -2: begin
               if x_intercept( last_vertex, next_vertex, pt.y2D ) > 
                           pt.x2D then begin
                  delta := -delta;
               end;
            end;
            otherwise begin
            end;
         end;
         angle := angle + delta;
         quad := next_quad;
         last_vertex := next_vertex;
      end;
      PointInPlaneInPolygon := (angle = 4) | (angle = -4);
   end;
   
Intersect
   function Intersect(const ray: Ray3D; const poly: MyPolygon; 
         const poly_extra: PolygonExtra; var distance : float; 
         var intersectionPt: My3DPoint) : boolean;
      var
         tempVector : My3DPoint;
         temp1, temp2 : float;
         intersectionPoint : My3DPoint;
         intersection2D : My2DPoint;
         Ib, Ic, Id: float;
   begin
      Intersect := false;

      { intersect ray with sphere }
      SubtractVectors( ray.origin, poly_extra.center,
                            tempVector );
      Ib := 2 * DotProduct( ray.direction, tempVector );
      Ic := DotProduct( tempVector, tempVector ) - 
                            poly_extra.radius2;
      Id := sqr(Ib) - 4.0*Ic;
      if Id >= 0 then begin { yes, ray intersects sphere }
         temp1 := DotProduct( poly.polyPlane.planeOrigin, 
                            poly_extra.normal ) - 
                     DotProduct( poly_extra.normal, ray.origin );
         temp2 := DotProduct(ray.direction, poly_extra.normal);
         if temp2 <> 0 then begin
            distance := temp1 / temp2;
            if distance > 0 then begin
               ScaleVector(ray.direction, distance, intersectionPoint);
               AddVectors(intersectionPoint, ray.origin, 
                           intersectionPoint);
               
               if Distance2(intersectionPoint, poly_extra.center)
                  <= 
                                          poly_extra.radius2 then begin 
                  { intersection point is whithin sphere.  
                     Find out if it is actually in the polygon }
                  intersectionPt := intersectionPoint;
                  { First translate back to the origin }
                  SubtractVectors(intersectionPoint, 
                     poly.polyPlane.planeOrigin,intersectionPoint);
                  intersection2D.x2D := DotProduct(
                     intersectionPoint,
                        poly_extra.rotX );
                  intersection2D.y2D := DotProduct( 
                     intersectionPoint, 
                        poly_extra.rotY );
                  { Then check if it is whithin the polygon }
                  Intersect := PointInPlaneInPolygon
                                                      (intersection2D,poly);
               end;
            end;
         end;
      end;
   end;

InitProjection
   procedure InitProjection(
      const viewPoint: My3DPoint;(* viewpoint from which to project *)
      const illumPoint:My3DPoint;
                                 (* viewpoint from which to draw shadow *)
      storage: univ Ptr;         (* auxiliary storage preallocated for your use *)
      storageSize: longint       (* number of bytes of storage *)
   );
   begin
{$unused( viewPoint, illumPoint, storage, storageSize )}
   end;

PreparsePolygons
   procedure PreparsePolygons( my_storage: StorageRecordPtr;
   numPolys: longint; const thePolys: MyPolygonArray );
      var
         i, j: longint;
         pt: My3DPoint;
         pts: array[1..kMAXPOINTS] of My3DPoint;
         min_x, min_y, min_z, max_x, max_y, max_z: My3DPoint;
         dist_x, dist_y, dist_z, new_radius2: float;
         radius, new_radius, old_to_new: float;
         sinX, cosX, sinY, cosY, sinZ, cosZ: float;
   begin
      for i := 0 to numPolys-1 do begin
         with my_storage^.poly_extra[i], thePolys[i],
         polyPlane.planeNormal do begin
            sinX := sin(thetaX);
            cosX := cos(thetaX);
            sinY := sin(thetaY);
            cosY := cos(thetaY);
            sinZ := sin(thetaZ);
            cosZ := cos(thetaZ);
            normal.x3d := sinY*cosX;
            normal.y3d := -sinX;
            normal.z3d := cosY*cosX;
            rotX.x3D := 1;
            rotX.y3D := 0;
            rotX.z3D := 0;
            RotateZ(rotX, sinZ, cosZ, rotX);
            RotateX(rotX, sinX, cosX, rotX);
            RotateY(rotX, sinY, cosY, rotX);
            rotY.x3D := 0;
            rotY.y3D := 1;
            rotY.z3D := 0;
            RotateZ(rotY, sinZ, cosZ, rotY);
            RotateX(rotY, sinX, cosX, rotY);
            RotateY(rotY, sinY, cosY, rotY);
            
            for j := 1 to numPoints do begin
               pt.x3D := thePoint[j-1].x2D;
               pt.y3D := thePoint[j-1].y2D;
               pt.z3D := 0;
               RotateZ(pt, sinZ, cosZ, pt);
               RotateX(pt, sinX, cosX, pt);
               RotateY(pt, sinY, cosY, pt);
               pts[j] := pt;
               if j = 1 then begin
                  min_x := pt; min_y := pt; min_z := pt;
                  max_x := pt; max_y := pt; max_z := pt;
               end else begin
                  if pt.x3D < min_x.x3D then begin
                     min_x := pt;
                  end;
                  if pt.y3D < min_y.y3D then begin
                     min_y := pt;
                  end;
                  if pt.z3D < min_z.z3D then begin
                     min_z := pt;
                  end;
                  if pt.x3D > max_x.x3D then begin
                     max_x := pt;
                  end;
                  if pt.y3D > max_y.y3D then begin
                     max_y := pt;
                  end;
                  if pt.z3D > max_z.z3D then begin
                     max_z := pt;
                  end;
               end;
            end;
            
            dist_x := Distance2( min_x, max_x );
            dist_y := Distance2( min_y, max_y );
            dist_z := Distance2( min_z, max_z );
            if dist_x > dist_y then begin
               if dist_x > dist_z then begin
                  radius2 := dist_x/4;
                  MidPoint( min_x, max_x, center );
               end else begin
                  radius2 := dist_z/4;
                  MidPoint( min_z, max_z, center );
               end;
            end else begin
               if dist_y > dist_z then begin
                  radius2 := dist_y/4;
                  MidPoint( min_y, max_y, center );
               end else begin
                  radius2 := dist_z/4;
                  MidPoint( min_z, max_z, center );
               end;
            end;
            
            for j := 1 to numPoints do begin
               new_radius2 := Distance2( center, pts[j] );
               if new_radius2 > radius2 then begin
                  radius := sqrt(radius2);
                  new_radius := sqrt(new_radius2);
                  radius2 := (radius + new_radius)/2;
                  old_to_new := radius2 - radius;
                  center.x3D := (radius2*center.x3D + 
                              old_to_new*pts[j].x3D)/radius;
                  center.y3D := (radius2*center.y3D + 
                              old_to_new*pts[j].y3D)/radius;
                  center.z3D := (radius2*center.z3D + 
                              old_to_new*pts[j].z3D)/radius;
                  radius2 := sqr(radius2);
               end;
            end;
         
            AddVectors( polyPlane.planeOrigin, center, center );

         end;
      end;
   end;
   
CalcProjection
   procedure CalcProjection(
      offScreen: GWorldPtr;          (* GWorld to draw projection *)
      const thePolys: MyPolygonArray;(* polygons to project *)
      numPolys: longint;             (* number of polygons to project *)
      const viewPoint: My3DPoint;    (* viewpoint from which to project *)
      const illumPoint: My3DPoint;   (* illumination point from which to draw shadow *)
      storage: univ Ptr;         (* auxiliary storage preallocated for your use *)
      storageSize: longint      (* number of bytes of storage *)
   );
      var
         bounds: Rect;
         x, y : integer;
         colour : RGBColor;
         viewRay : Ray3D;
         lightRay : Ray3D;
         i : integer;
         closestDistance : float;
         closestIntersectionPt: My3DPoint;
         thisDistance : float;
         intersectionPt: My3DPoint;
         intersect_polygon: longint;
         pm: PixMapHandle;
         junk_boolean: boolean;
         pixels: Ptr;
         rowbytes_add: longint;
         my_storage: StorageRecordPtr;
   begin
{$unused( storage, storageSize )}
      my_storage := StorageRecordPtr(storage);

      PreparsePolygons( my_storage, numPolys, thePolys );

      SetGWorld( offScreen, nil );
      bounds := offScreen^.PortRect;
      pm := GetGWorldPixMap( offScreen );
      junk_boolean := LockPixels( pm );
      pixels := GetPixBaseAddr( pm );
      rowbytes_add := band( pm^^.rowBytes, $3FFF ) - 
                                    4 * (bounds.right - bounds.left);

      for y := bounds.top to bounds.bottom-1 do begin
         for x := bounds.left to bounds.right-1 do begin
            MakeViewRay(viewPoint, x, y, 0, viewRay);
            closestDistance := 0.0;
            intersect_polygon := -1;
            for i:= 1 to numPolys do begin
               if Intersect(viewRay, thePolys[i-1], 
                           my_storage^.poly_extra[i-1], thisDistance, 
                           intersectionPt) then begin
                  if (thisDistance > closestDistance) then begin
                     intersect_polygon := i;
                     closestDistance := thisDistance;
                     closestIntersectionPt := intersectionPt;
                  end;
               end
            end;
            if intersect_polygon > 0 then begin
               colour := thePolys[intersect_polygon-1].polyColor;

               MakeViewRay(illumPoint, closestIntersectionPt.x3D, 
                                 closestIntersectionPt.y3D, 
                                 closestIntersectionPt.z3D, lightRay);

               for i:= 1 to numPolys do begin
                  if (intersect_polygon <> i) & 
                     Intersect(lightRay, thePolys[i-1], 
                     my_storage^.poly_extra[i-1], 
                     thisDistance, intersectionPt) then begin
               colour.red := band(colour.red, $0FFFF) div 2;
               colour.green := band(colour.green, $0FFFF) div 2;
               colour.blue := band(colour.blue, $0FFFF) div 2;
                     leave;
                  end
               end;
               
      LongintPtr(pixels)^ := bsl( band(colour.red, $0FF00), 8 ) 
                     + band(colour.green, $0FF00) + 
                        bsr( band(colour.blue, $0FF00), 8 );
            end else begin
               LongintPtr(pixels)^ := 0;
            end;
            longint(pixels) := longint(pixels) + 4;
         end;
         longint(pixels) := longint(pixels) + rowbytes_add;
      end;
   end;

end.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

iDefrag 5.0.0 - Disk defragmentation and...
iDefrag helps defragment and optimize your disk for improved performance. Features include: Supports HFS and HFS+ (Mac OS Extended). Supports case sensitive and journaled filesystems. Supports... Read more
PCalc 4.2 - Full-featured scientific cal...
PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more
FileZilla 3.10.2 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.10.2: Note: Now requires a 64-bit Intel processor.... Read more
The Hit List 1.1.11 - Advanced reminder...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
Bartender 1.2.32 - Organize your menu ba...
Bartender lets you organize your menu bar apps. Features: Lets you tidy your menu bar apps how you want. See your menu bar apps when you want. Hide the apps you need to run, but do not need to... Read more
ClamXav 2.7.5 - Free virus checker, base...
ClamXav is a free virus checker for OS X. It uses the tried, tested, and very popular ClamAV open source antivirus engine as a back end. I hope you like and use ClamXav a lot and that it helps keep... Read more
xScope 4.1.2 - Onscreen graphic measurem...
xScope is powerful set of tools that are ideal for measuring, inspecting, and testing on-screen graphics and layouts. Its tools float above your desktop windows and can be accessed via a toolbar,... Read more
MacFamilyTree 7.3.3 - Create and explore...
MacFamilyTree gives genealogy a facelift: it's modern, interactive, incredibly fast, and easy to use. We're convinced that generations of chroniclers would have loved to trade in their genealogy... Read more
Skype 7.5.0.738 - Voice-over-internet ph...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
PushPal 3.0 - Mirror Android notificatio...
PushPal is a client for Pushbullet, which automatically shows you all of your phone's notifications right on your computer. This means you can see who's calling or read text messages even if your... Read more

Dungeon Hunter 5 Coming on March 12
Gameloft has excitedly announced that Dungeon Hunter 5 is on its way! Once again, you will adventure across the land of Valenthia exploring dungeons and fighting monsters. The game will have a new asynchronous multiplayer mode called Strongholds... | Read more »
It Came From Canada: Jurojin: Immortal N...
At this point it’s pretty safe to say that no MOBA is going to dethrone Dota 2 and League of Legends anytime soon. After all, if Batman can’t do it, nobody can. However, with a genre as popular and profitable as this one, there’s still room for... | Read more »
Tiny Farm – Animals, Tractors and Advent...
Tiny Farm – Animals, Tractors and Adventures! Review By Amy Solomon on March 3rd, 2015 Our Rating: :: LIVELY LANDSCAPESUniversal App - Designed for iPhone and iPad Tiny Farm – Animals, Tractors and Adventures! includes farm-related... | Read more »
This Week at 148Apps: February 23-27, 20...
Final February Fun at 148Apps   How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you’re looking for. The ones we love become Editor’s Choice, standing out... | Read more »
GDC 2015 – Does Not Commute is Definitel...
GDC 2015 – Does Not Commute is Definitely a Game You Should Keep an Eye on Posted by Rob Rich on March 2nd, 2015 [ permalink ] We were teased about Mediocre Games’ (Smash Hit, | Read more »
F84 Games & POW! Announce Stan Lee V...
F84 Games has announced that it is working with legendary comic creator Stan Lee and POW! Entertainment to produce Stan Lee’s Hero Command. The game will be a action adventure of heroic proportions. | Read more »
Setlyst Keeps Your Set Straight So You C...
Setlyst Keeps Your Set Straight So You Can Focus On Rocking Out. Posted by Jessica Fisher on March 2nd, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Space is Vast, So Space Agency Has a Vas...
Space is Vast, So Space Agency Has a Vast New Update! Posted by Jessica Fisher on March 2nd, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Size DOES Matter Review
Size DOES Matter Review By Campbell Bird on March 2nd, 2015 Our Rating: :: HARD TO BEATUniversal App - Designed for iPhone and iPad This rhythm game has a unique control scheme and performance system that make it feel like a true... | Read more »
The first ever action 3D card battler Al...
On the other hand, you probably haven’t played an action 3D card battler – until now. Step forward, All Star Legion. All Star Legion is a 3D QTE-based action RPG card battler, but fear not – the game itself isn’t as convoluted as its description.... | Read more »

Price Scanner via MacPrices.net

Another Tranche Of IBM MobileFirst For iOS Ap...
IBM has announced the next expansion phase for  its IBM MobileFirst for iOS portfolio, with a troika of new apps to address key priorities for the Banking and Financial Services, Airline and Retail... Read more
Sale! 15-inch Retina MacBook Pros for up to $...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for up to $250 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $... Read more
WaterField Designs Introduces the Minimalist...
With Apple Pay gaining popularity, Android Pay coming in May 2015, and loyalty cards and receipts that can be accessed from smartphones, San Francisco’s WaterField Designs observes that it may be... Read more
Sale! 15-inch 2.2GHz Retina MacBook Pro for $...
 Best Buy has the 15″ 2.2GHz Retina MacBook Pro on sale for $1774.99 $1799.99, or $225 off MSRP. Choose free home shipping or free local store pickup (if available). Price valid for online orders... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $170 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999.99 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more
27-inch 3.5GHz 5K iMac in stock today and on...
 B&H Photo has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP, and it’s the lowest price available for... Read more
Apple Launches Free Web-Based Pages and Other...
Apple’s new Web-only access to iWork productivity apps is a free level of iCloud service available to anyone, including people who don’t own or use Apple devices. The service includes access to Apple... Read more
Survey Reveals Solid State Disk (SSD) Technol...
In a recent SSD technology use survey, Kroll Ontrack, a firm specializing in data recovery, found that while nearly 90 percent of respondents leverage the performance and reliability benefits of SSD... Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Pay Automation Engineer - iOS System...
**Job Summary** At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring passion and dedication to your job Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Event Director, *Apple* Retail Marketing -...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global engagement strategy and team. Delivering an overarching brand Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.