Added image pigment.

[raymarcher.git] / Textures.lua

diff --git a/Textures.lua b/Textures.lua
index 2b2e701..ccc7dbc 100644 (file)
--- a/Textures.lua
+++ b/Textures.lua
@@ -63,16 +63,63 @@ local function make_solid_pigment(colour)
    end
 end
 
-local function make_checkered_pigment(colour1, colour2)
+local function make_checkered_pigment(pigment1, pigment2)
    return function(x,y)
       if (x%1 < 0.5 and y%1 < 0.5) or (x%1 > 0.5 and y%1 > 0.5) then
-         return colour1
+         return pigment1(x,y)
       else
-         return colour2
+         return pigment2(x,y)
       end
    end
 end
 
+local function make_image_pigment(filename,scale)
+
+   print("Loading image pigmant from '" .. filename .. "'...")
+
+   local f = assert(io.open(filename, "rb"))
+   local data = f:read("*all")
+   f:close()
+
+   local start,_,wstr,hstr,dstr,raster =
+      string.find(data, "^P6[%s%c]+(%d+)[%s%c]+(%d+)[%s%c]+(%d+)[%s%c](.*)$")
+
+   if start ~= 1 then
+      error("Error reading image. Is it in PPM(P6) format?")
+   end
+
+   if dstr ~= "255" then
+      error("Only images with a depth of 255 are supported.")
+   end
+
+   local width = tonumber(wstr)
+   local height = tonumber(hstr)
+   local depth = tonumber(dstr)
+
+   local pixels = {}
+   local i = 1
+   for triple in string.gmatch(raster, "...") do
+      local _,_,r,g,b = string.find(triple, "(.)(.)(.)")
+      pixels[i] = {string.byte(r)/depth, string.byte(g)/depth, string.byte(b)/depth}
+      i = i + 1
+   end
+   
+   print("done.")
+   print("(Read " .. tostring(#pixels) .. " pixels.)")
+
+   local pixels_per_unit = math.max(width,height)
+
+   return function(x,y)
+      local xi = math.floor(((x+0.5)*pixels_per_unit/scale)%width) + 1
+      local yi = math.floor(((y+0.5)*pixels_per_unit/scale)%height) + 1
+      local i = width*(yi-1) + xi
+      if pixels[i] == nil then
+         error("Pixel not found at xi=" .. tostring(xi) .. " yi=" .. tostring(yi))
+      end
+      return pixels[i]
+   end
+end
+
 local function make_mandelbrot_pigment(set_pigment, nonset_pigment, max_iter)
 
    local function get_col(x,y,cx,cy,iter)