don't create rectangles with width or height being 0 (and some whitespace noise, sorry)

animations/mherweg.c

@@ -201,11 +201,12 @@ static void rectangles()
 	clear_screen(blank);
 	for (unsigned char n = 0; n < 60; n++)
 	{
-		// randomly chosen position, dimension and color
+		// randomly choose position, dimensions and color (the rectangle may
+		// exceed the actual screen size, only width and height have to be > 0)
 		unsigned char const x = random8() % NUM_COLS;
 		unsigned char const y = random8() % NUM_ROWS;
-		unsigned char const h = random8() % NUM_COLS / 2;
-		unsigned char const w = random8() % NUM_ROWS / 2;
+		unsigned char const w = random8() % (NUM_COLS / 2) + 1;
+		unsigned char const h = random8() % (NUM_ROWS / 2) + 1;
 		unsigned char const color = random8() % (NUMPLANE + 1);
 
 		filled_rectangle((pixel){x, y}, w, h, color);
@@ -225,16 +226,16 @@ static void lines1()
 	clear_screen(blank);
 	for (unsigned char n = 0; n < 200; n++)
 	{
-		// randomly chosen position, dimension and color
-		unsigned char const x = random8() % NUM_COLS;
-		unsigned char const y = random8() % NUM_ROWS;
-		unsigned char const h = random8() % NUM_COLS;
-		unsigned char const w = random8() % NUM_ROWS;
+		// randomly choose position, length and color
+		unsigned char const x1 = random8() % NUM_COLS;
+		unsigned char const y1 = random8() % NUM_ROWS;
+		unsigned char const x2 = random8() % NUM_COLS;
+		unsigned char const y2 = random8() % NUM_ROWS;
 		unsigned char const color = random8() % (NUMPLANE + 1);
 
-		line((pixel){x, y}, (pixel){w, h}, color);
+		line((pixel){x1, y1}, (pixel){x2, y2}, color);
 		wait(random8()); // wait up to 250 ms
-		line((pixel){x, y}, (pixel){w, h}, blank);
+		line((pixel){x1, y1}, (pixel){x2, y2}, blank);
 	}
 }
 
@@ -264,7 +265,7 @@ static void dots1()
 			wait(glimmer_delay);
 		}
 
-		// wait up to 2500 ms until the next dot is drawn
+		// wait up to 2.5 seconds until the next dot is drawn
 		wait(random8() * 10);
 	}
 }