Data commit

Task/Death-Star/Yabasic/death-star.basic

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+open window 100,100
+window origin "cc"
+backcolor 0,0,0
+clear window
+
+tonos = 100
+interv = int(255 / tonos)
+dim shades(tonos)
+
+shades(1) = 255
+for i = 2 to tonos
+	shades(i) = shades(i-1) - interv
+next i
+
+dim light(3)
+
+light(0) = 30
+light(1) = 30
+light(2) = -50
+
+
+sub normalize(v())
+    local long
+	
+    long = sqrt(v(0)*v(0) + v(1)*v(1) + v(2)*v(2))
+    v(0) = v(0) / long
+    v(1) = v(1) / long
+    v(2) = v(2) / long
+end sub
+
+
+sub punto(x(), y())
+    local d
+
+    d = x(0)*y(0) + x(1)*y(1) + x(2)*y(2)
+    if d < 0 then
+    	return -d
+    else
+    	return 0
+    end if
+end sub
+
+
+//* positive shpere and negative sphere */
+dim pos(3)
+dim neg(3)
+
+// x, y, z, r
+
+pos(0) = 10
+pos(1) = 10
+pos(2) = 0
+pos(3) = 20
+
+neg(0) = 0
+neg(1) = 0
+neg(2) = -5
+neg(3) = 15
+
+
+sub hit_sphere(sph(), x, y)
+	local zsq
+	
+	x = x - sph(0)
+	y = y - sph(1)
+	zsq = sph(3) * sph(3) - (x * x + y * y)
+	if (zsq < 0) then
+		return 0
+	else
+		return sqrt(zsq)
+	end if
+end sub
+
+
+sub draw_sphere(k, ambient)
+    local i, j, intensity, hit_result, result, b, vec(3), x, y, zb1, zb2, zs1, zs2, ini1, fin1, ini2, fin2
+	
+    ini1 = int(pos(1) - pos(3))
+    fin1 = int(pos(1) + pos(3) + .5)
+    for i = ini1 to fin1
+        y = i + .5
+        ini2 = int(pos(0) - 2 * pos(3))
+        fin2 = int(pos(0) + 2 * pos(3) + .5)
+        for j = ini2 to fin2
+            x = (j - pos(0)) / 2 + .5 + pos(0)
+
+            // ray lands in blank space, draw bg
+            result = hit_sphere(pos(), x, y)
+
+            if not result then
+		hit_result = 0
+
+		//* ray hits pos sphere but not neg, draw pos sphere surface */
+	    else
+		zb1 = pos(2) - result
+		zb2 = pos(2) + result
+		result = hit_sphere(neg(), x, y)
+		if not result then
+		    hit_result = 1
+		else
+		    zs1 = neg(2) - result
+		    zs2 = neg(2) + result
+		    if (zs1 > zb1) then
+			hit_result = 1
+		    elseif (zs2 > zb2) then
+			hit_result = 0
+		    elseif (zs2 > zb1) then
+			hit_result = 2
+		    else
+			hit_result = 1
+		    end if
+		end if
+	    end if
+	
+  	    if not hit_result then
+  	        color 0,0,0
+  	        dot x, y
+  	    else
+	        switch(hit_result)
+	        case 1:
+		    vec(0) = x - pos(0)
+		    vec(1) = y - pos(1)
+		    vec(2) = zb1 - pos(2)
+		    break
+	        default:
+		    vec(0) = neg(0) - x
+		    vec(1) = neg(1) - y
+		    vec(2) = neg(2) - zs2
+	        end switch
+				
+                normalize(vec())
+                b = (punto(light(), vec())^k) + ambient
+                intensity = (1 - b) * tonos
+                if (intensity < 1) intensity = 1
+                if (intensity > tonos) intensity = tonos
+                color shades(intensity),shades(intensity),shades(intensity)
+                dot x,y
+            end if
+        next j
+    next i
+end sub
+
+
+ang = 0
+
+while(true)
+	//clear window
+	light(1) = cos(ang * 2)
+	light(2) = cos(ang)
+	light(0) = sin(ang)
+	normalize(light())
+	ang = ang + .05
+
+	draw_sphere(2, .3)
+wend