CON: always return non-negative values from 'clipmove' and related.

Previously, the C function clipmove() returned negative values when hit a
wall (32768+wallnum) or sprite (49152+spritenum) because internally,
these values were encoded into a *signed* 16-bit integer. This made no
difference to C code using it, since it always proceeded by bit checks,
but was inconsistent with documentation on CON 'clipmove' on the wiki.

The following commands are affected too, since they use the value returned
by clipmove(): 'clipmovenoslide', 'movesprite'. Also, the value of
actor[].movflag ('htmovflag' from CON).

Also, fix 'clipmove*' in LunaCON and add lunatic/test/checknearwall.con
as an example of how to implement a being-close-to-a-wall checker as
requested in
http://forums.duke4.net/topic/7869-determining-closeness-to-a-wall/

git-svn-id: https://svn.eduke32.com/eduke32@4874 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/build/src/engine.c

@@ -2330,8 +2330,8 @@ static int32_t colnext[256];
 static char coldist[8] = {0,1,2,3,4,3,2,1};
 static int32_t colscan[27];
 
-static int16_t clipnum, hitwalls[4];
+static int16_t clipnum;
-const int32_t hitscangoalx = (1<<29)-1, hitscangoaly = (1<<29)-1;
+static const int32_t hitscangoalx = (1<<29)-1, hitscangoaly = (1<<29)-1;
 #ifdef USE_OPENGL
 int32_t hitallsprites = 0;
 #endif
@@ -13611,7 +13611,7 @@ int32_t clipmove(vec3_t *pos, int16_t *sectnum,
     int32_t i, j, k, tempint1, tempint2;
     int32_t x1, y1, x2, y2;
     int32_t dax, day;
-    int32_t hitwall, cnt, retval=0;
+    int32_t retval=0;
 
     spritetype *curspr=NULL;  // non-NULL when handling sprite with sector-like clipping
     int32_t curidx=-1, clipsectcnt, clipspritecnt;
@@ -13933,8 +13933,9 @@ int32_t clipmove(vec3_t *pos, int16_t *sectnum,
     }
 #endif
 
-    hitwall = 0;
+    int32_t hitwalls[4], hitwall;
-    cnt = clipmoveboxtracenum;
+    int32_t cnt = clipmoveboxtracenum;
+
     do
     {
         int32_t intx=goalx, inty=goaly;
@@ -13977,7 +13978,8 @@ int32_t clipmove(vec3_t *pos, int16_t *sectnum,
             xvect = (goalx-intx)<<14;
             yvect = (goaly-inty)<<14;
 
-            if (cnt == clipmoveboxtracenum) retval = clipobjectval[hitwall];
+            if (cnt == clipmoveboxtracenum)
+                retval = (uint16_t)clipobjectval[hitwall];
             hitwalls[cnt] = hitwall;
         }
         cnt--;

polymer/eduke32/source/lunatic/control.lua

@@ -1539,7 +1539,7 @@ end
 function _clipmovex(x, y, z, sectnum, xv, yv, wd, cd, fd, clipmask, noslidep)
     check_sector_idx(sectnum)
     local ipos = ivec3(x, y, z)
-    local sect = ffi.new("int16_t [1]")
+    local sect = ffi.new("int16_t [1]", sectnum)
     local ret = ffiC.clipmovex(ipos, sect, xv, yv, wd, cd, fd, clipmask, noslidep)
     -- Return: clipmovex() return value; updated x, y, sectnum
     return ret, ipos.x, ipos.y, sect[0]

polymer/eduke32/source/lunatic/lunacon.lua

@@ -3546,6 +3546,8 @@ local Grammar = Pat{
                            + Range("09")^1)
                              ) / parse_number,
 
+    -- TODO: negated gamevars. Currently, "-var" is parsed as a negated label.
+
     t_identifier_all = lpeg.C(t_broken_identifier + t_good_identifier),
     -- NOTE: -conl.keyword alone would be wrong, e.g. "state breakobject":
     -- NOTE 2: The + "[" is so that stuff like

polymer/eduke32/source/lunatic/test/checknearwall.con

@@ -0,0 +1,86 @@
+
+// Inputs to "state checknearwall".
+gamevar wd 128 0  // wall distance
+gamevar cfd 1024 0  // ceiling/floor distance
+
+// Outputs of "state checknearwall".
+gamevar hitwall -1 0
+
+// Temporary variables.
+gamevar tmp 0 0
+gamevar ret 0 0
+gamevar x 0 0
+gamevar y 0 0
+gamevar z 0 0
+gamevar sectnum 0 0
+
+define CM_BLK_WAL 1
+
+state getcoords
+    setvarvar x sprite[THISACTOR].x
+    setvarvar y sprite[THISACTOR].y
+    setvarvar z sprite[THISACTOR].z
+    setvarvar sectnum sprite[THISACTOR].sectnum
+ends
+
+// Inputs: (wd, cfd)
+// Returns: hitwall
+//  -1: hit no wall
+// >=0: hit that wall
+state checknearwall
+    setvar hitwall -1
+
+    setvarvar tmp wd, shiftvarl tmp 14
+
+    state getcoords
+    clipmovenoslide ret (x, y, z, sectnum) (tmp, 0) (wd, cfd, cfd) CM_BLK_WAL
+    ifvarn ret 0 { setvarvar hitwall ret, subvar hitwall 32768, break }
+
+    state getcoords
+    clipmovenoslide ret (x, y, z, sectnum) (0, tmp) (wd, cfd, cfd) CM_BLK_WAL
+    ifvarn ret 0 { setvarvar hitwall ret, subvar hitwall 32768, break }
+
+    mulvar tmp -1
+
+    state getcoords
+    clipmovenoslide ret (x, y, z, sectnum) (tmp, 0) (wd, cfd, cfd) CM_BLK_WAL
+    ifvarn ret 0 { setvarvar hitwall ret, subvar hitwall 32768, break }
+
+    state getcoords
+    clipmovenoslide ret (x, y, z, sectnum) (0, tmp) (wd, cfd, cfd) CM_BLK_WAL
+    ifvarn ret 0 { setvarvar hitwall ret, subvar hitwall 32768, break }
+ends
+
+////////// Example usage //////////
+
+onevent EVENT_PROCESSINPUT
+    state checknearwall
+endevent
+
+
+define Q_tmp 500
+definequote Q_tmp <write on me>
+
+define Q_no 501
+definequote Q_no Hit no wall
+
+define Q_yes 502
+definequote Q_yes Hit wall %d
+
+define Q_info 503
+definequote Q_info pos: %d %d %d sect: %d
+
+onevent EVENT_DISPLAYREST
+    qsprintf Q_tmp Q_info, x y z sectnum
+    minitext (100, 8) Q_tmp (0, 0)
+
+    ifvarn hitwall -1
+    {
+        qsprintf Q_tmp Q_yes hitwall
+        minitext (100, 16) Q_tmp (0, 0)
+    }
+    else
+    {
+        minitext (100, 16) Q_no (0, 0)
+    }
+endevent