More .obj investigation. Looking for records in sprite data

doc/formats/obj.md

@@ -251,16 +251,24 @@ d: 116 * 100 = 11600. 7368 - 24 = 7344.  5.1 bits  / pixel
 We still don't know what the first 32 bits are all about. Perhaps they can help
 to explain the differences in putative bpp.
 
-0x002-0x003 changes in step with total number of pixels?
+0x002-0x003 changes in step with total number of pixels, but that doesn't seem
+to account for the difference.
 
-| ID | 0x2-0x3 | dec LE | Number of pixels |
-| -- | ------- | ------ | ---------------- |
-| a  |  61 01  | 353    |     1 |
-| b  |  25 01  | 293    |  3312 |
-| d  |  19 01  | 281    | 11600 |
-| c  |  16 01  | 278    | 11948 |
+Considering sprites with a 1,1 x,y.
+
+```
+           u0 u1 u2 u3 X  Y    pixeldata
+bgtree_m 24 : ee 00 5e 01 01 01   01 1f 00
+blank     0 : 10 01 61 01 01 01   01 fd 00
+transpix  0 : 11 01 3c 01 01 01   01 ae 00
+```
+
+Sprites seem to end with a \x00 byte in-general, but we *only* see 0x01 in the
+first byte of data for these 1x1 tiles.
+
+Sprites with `X= 128 Y=63` *almost always* seem to have a u0..u3 of
+`d1 00 42 01` with a few exceptions, e.g. `treemac{1,2}.obj`
 
-Not clear what it means. If anything!
 
 WH40K_TD.exe loops around "ReadInMissionFLCs", incl. address 0x0041dd10, where
 it loads in all the .asc and .obj files in a set.

scripts/try-uncompress

@@ -251,55 +251,39 @@ end
 #   * RLE8: https://www.fileformat.info/format/bmp/corion-rle8.htm
 
 def decompress(filename)
-  puts "\nAttempting RLE decompression of #{filename}..."
+  puts "\nAttempting custom decompression of #{filename}..."
 
   obj = load_obj(filename)
 
   obj.sprites.each_with_index do |sprite, i|
-    print "Sprite %02d..."%i
+    hdr = sprite.header
+    print "Sprite %02d... x=#{hdr.width} y=#{hdr.height}"%i
 
     decompressed = []
     data = sprite.data.bytes
     hdr = sprite.header
 
-    (0...hdr.height).each do |i|
-   #   npackets = data.shift(1)[0] # ignore the packet byte
-      decompressed_line = []
+    loop do
+      break if data.empty?
 
-      count = 0
-      loop do
-        cmd = data.shift(1)[0]
-        if cmd == 0 # end of stream
-          print "Done! #{data.size} bytes left. "
-          break
-        elsif cmd == nil
-          print "Ran out of data! "
-          break
-        elsif cmd > 128 # "negative" bytes say "copy abs(X) bytes unmodified from input to output"
-          decompressed_line.concat(data.shift(cmd-128))
-        else # "positive" bytes say "repeat the next byte X times"
-          decompressed_line.concat(data.shift(1)*cmd)
-        end
+      type = data.shift(1)[0]
+      right = data.index(0)
+      
 
-        if decompressed_line.size == hdr.width
-          print "Done line! "
-          break
-        end
-
-     #   if npackets > 0 && count == npackets
-      #    print "Done packets! "
-     #     break
-      #  end
-
-        count+=1
+      if right.nil?
+        print "error! end of chunk not found"
+        break
       end
 
-      raise "Bad length for line #{i}! #{decompressed_line.size} (Expected #{hdr.width})" if decompressed_line.size != hdr.width
-      decompressed << decompressed_line
+      rec = data.shift(right)
+      _ = data.shift(1) # drop the record separator
+
+      decompressed << [ type, rec[0] ]
     end
 
-    puts "Decompressed: #{decompressed.flatten.size} bytes. Sprite pixels: #{hdr.width*hdr.height}"
-    #display(decompressed.map(&:chr).join(""))
+    puts ": #{data.size} bytes remaining. Decompressed: #{decompressed.size} bytes. Sprite pixels: #{hdr.width*hdr.height}"
+    pp decompressed
+#    display(decompressed.map(&:chr).join(""))
   end
 end
 
@@ -318,23 +302,47 @@ def compare(filenames)
 
     end
 end
+require 'set'
+def correlate(filenames)
+  objs = filenames.map { |f| load_obj(f) }
+
+  results = Hash.new { |h,k| h[k] = Set.new }
+
+
+  objs.each do |obj|
+    obj.sprites.each do |spr|
+      results[spr.header.unknown0 & 0xffff] << spr.header.width
+    end
+  end
+
+  puts "Unique widths for u0,1"
+  pp results
+end
 
 def sprites(filename)
   obj = load_obj(filename)
 
   puts filename + ":"
-    puts "\ti   X   Y   Px   bytes bits/px"
   obj.sprites.each_with_index do |spr, i|
     hdr = spr.header
     px = hdr.width * hdr.height
+    
 
-    puts "\t%02d: %03d %03d %04d %04d  %.2f"%[
+    puts "%s %03d: %02x %02x %02x %02x %3d %3d %5d %5d  %.2f     %02x %02x ... %02x"%[
+      filename,
       i,
+      hdr.unknown0 & 0x000000ff,
+      (hdr.unknown0 & 0x0000ff00) >> 8,
+      (hdr.unknown0 & 0x00ff0000) >> 16,
+      (hdr.unknown0 & 0xff000000) >> 24,
       hdr.width,
       hdr.height,
       px,
       hdr.size,
-      (hdr.size*8) / px.to_f
+      (hdr.size*8) / px.to_f,
+      spr.data.bytes[0],
+      spr.data.bytes[1],
+      spr.data.bytes[-1],
     ]
   end
 end
@@ -345,9 +353,11 @@ when "sprites" then
 when "dump" then
   ARGV.each { |filename| dump(filename) } 
 when "compare" then
-  compare(filenames)
+  compare(ARGV)
 when "decompress" then
   ARGV.each { |filename| decompress(filename) }
+when "correlate" then
+  correlate(ARGV)
 else
   puts "Unrecognized command #{command}"
   exit(1)