gradient

include/tools.bm

@@ -222,3 +222,71 @@ sub floodfill (startx,starty,fillcolor~&)
     wend
 end sub
 
+sub ditheredgradient (x1 as long,y1 as long,x2 as long,y2 as long,fcol as _unsigned long,bcol as _unsigned long)
+    ' 1. Get canvas boundaries from the active drawing layer
+    dim canvasw as integer:canvasw=_width(layers(1).ihandle)
+    dim canvash as integer:canvash=_height(layers(1).ihandle)
+
+    ' 2. Calculate vector properties of the drawn line
+    dim dx as single:dx=x2-x1
+    dim dy as single:dy=y2-y1
+    dim linelensq as single:linelensq=(dx*dx)+(dy*dy)
+
+    ' If the user didn't drag the mouse anywhere, just paint a solid pixel and exit
+    if linelensq=0 then
+        pset (x1,y1),fcol
+        exit sub
+    end if
+
+    ' 3. Extract RGB components of Foreground and Background colors
+    dim fr as integer:fr=_red(fcol)
+    dim fg as integer:fg=_green(fcol)
+    dim fb as integer:fb=_blue(fcol)
+
+    dim br as integer:br=_red(bcol)
+    dim bg as integer:bg=_green(bcol)
+    dim bb as integer:bb=_blue(bcol)
+
+    ' 4. Define a standard 4x4 Bayer Dithering Matrix (scaled 0 to 15)
+    dim bayer(3,3) as integer
+    bayer(0,0)=0:bayer(0,2)=8:bayer(0,1)=2:bayer(0,3)=10
+    bayer(2,0)=12:bayer(2,2)=4:bayer(2,1)=14:bayer(2,3)=6
+    bayer(1,0)=3:bayer(1,2)=11:bayer(1,1)=1:bayer(1,3)=9
+    bayer(3,0)=15:bayer(3,2)=7:bayer(3,1)=13:bayer(3,3)=5
+
+    ' 5. Loop through every single pixel on the canvas layer
+    dim x as long,y as long
+    dim t as single,threshold as single
+    dim targetr as integer,targetg as integer,targetb as integer
+    dim mixedcolor as _unsigned long
+
+    for y=0 to canvash-1
+        for x=0 to canvasw-1
+            ' Project current pixel onto the line vector to get interpolation factor 't'
+            t=((x-x1)*dx+(y-y1)*dy)/linelensq
+
+            ' Clamp t strictly between 0.0 and 1.0
+            if t<0 then t=0
+            if t>1 then t=1
+
+            ' Get the ordered dither adjustment ratio (-0.5 to +0.5 range influence)
+            threshold=(bayer(x mod 4,y mod 4)/16.0)-0.5
+
+            ' Apply blend factor altered by our dither threshold noise
+            dim blend as single:blend=t+threshold
+            if blend<0 then blend=0
+            if blend>1 then blend=1
+
+            ' Linearly interpolate colors
+            targetr=fr+(br-fr)*blend
+            targetg=fg+(bg-fg)*blend
+            targetb=fb+(bb-fb)*blend
+
+            ' Find the absolute closest matching color available in your specific palette
+            mixedcolor=closestcolor(_rgb32(targetr,targetg,targetb),pal())
+
+            ' Draw directly onto the destination image
+            pset (x,y),mixedcolor
+        next x
+    next y
+end sub