Data commit

Task/Draw-a-sphere/Smalltalk/draw-a-sphere.st

@@ -0,0 +1,63 @@
+Point3D :=
+   Point subclass:#Point3D
+        instanceVariableNames:'z'
+        classVariableNames:''
+        poolDictionaries:''
+        category:''
+        inEnvironment:nil.
+
+Point3D compile:'z ^ z'.
+Point3D compile:'z:v z := v'.
+
+normalize := [:v | |invLen|
+    invLen := 1 / (dot value:v value:v) sqrt.
+    v x: v x * invLen.
+    v y: v y * invLen.
+    v z: v z * invLen.
+].
+
+dot := [:a :b |
+    (a x * b x) + (a y * b y) + (a z * b z)
+].
+
+drawSphere := [:r :k :amb :dir |
+    |w h imh vec img|
+
+    w := r*4. h := r*3.
+    img := Image width:w height:h depth:8.
+    img photometric:#blackIs0; createPixelStore.
+    vec := Point3D new.
+    0-r to:r do:[:x |
+        0-r to:r do:[:y |
+            |z s lum|
+            (z := (r*r) - (x*x) - (y*y)) >= 0 ifTrue:[
+                vec x: x.
+                vec y: y.
+                vec z: z sqrt.
+                normalize value:vec.
+                s := dot value:dir value:vec.
+                s < 0 ifTrue:[ s := 0 ].
+                lum := 255 * ((s raisedTo: k) + amb) / (1 + amb).
+                lum < 0 ifTrue:[
+                    lum := 0
+                ] ifFalse:[ lum > 255 ifTrue:[
+                    lum := 255
+                ]].
+                img atX:(x+(w//2)) y:(y+(h//2)) put:(Color greyByte:lum).
+            ]
+        ]
+    ].
+    img
+].
+
+main := [
+    |dir img|
+
+    dir := Point3D new x:-30; y:-30; z:50; yourself.
+    normalize value:dir.
+    img := drawSphere value: 100 value: 1.5 value: 0.2 value: dir.
+    img displayOn:(View new extent:400@400; openAndWait).
+    img saveOn:'sphere.png'.
+].
+
+main value.