Added grid render.

Added particle toggle.
Added boundary shape adjustment.

utils/clamp.go

@@ -0,0 +1,27 @@
+package utils
+
+// returns adjusted value between start and end, whichever is closer
+// unless value is between, in which case it returns value
+func Clamp(value, start, end int) int {
+	if value < start {
+		return start
+	}
+
+	if value < end {
+		return value
+	}
+
+	return end
+}
+
+func Clamp32(value, start, end float32) float32 {
+	if value < start {
+		return start
+	}
+
+	if value < end {
+		return value
+	}
+
+	return end
+}