From: Ben Harris <bjh21@bjh21.me.uk>
Date: Tue, 25 Jul 2017 22:36:10 +0000 (+0100)
Subject: Add mechanisms (as yet unused) for varying Bedstead's weight.
X-Git-Tag: bedstead-002.000~121
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=78ccce6504a543401ceaa5df5143234830038f71;p=bedstead.git

Add mechanisms (as yet unused) for varying Bedstead's weight.

There are rather tight limits to the weights it can achieve, though.
---

diff --git a/bedstead.c b/bedstead.c
index 56ed868..8ba649e 100644
--- a/bedstead.c
+++ b/bedstead.c
@@ -1814,7 +1814,46 @@ emit_path()
 	}
 	if (started) printf("EndSplineSet\n");
 }
-		
+
+/*
+ * To vary the weight of Bedstead, we just vary the thickness of
+ * vertical strokes.  More precisely, we pretend that the weight
+ * variation is achieved by moving the rising edges of the output
+ * waveform of the SAA5050.  This is implemented by moving all left
+ * edges left and right.  The code below only handles cases where we
+ * don't run out of slack in horizontal lines, which limits weight to
+ * the range (-50 * SCALE) < weight < (25 * SCALE).
+ */
+static int weight = 0 * SCALE;
+
+static void
+adjust_weight()
+{
+	int i;
+	point *p;
+
+	for (i = 0; i < nextpoint; i++) {
+		p = &points[i];
+		if (p->next == NULL) continue;
+		assert(p->prev != NULL);
+		/* Move left-edge points horizontally */
+		if (p->prev->v.y <= p->v.y && p->v.y <= p->next->v.y)
+			p->v.x -= weight;
+		/* Move top inner corner points along NE/SW diagonal */
+		if (p->prev->v.y < p->v.y && p->v.y > p->next->v.y &&
+		    p->prev->v.x > p->v.x && p->v.x > p->next->v.x) {
+			p->v.x -= weight/2;
+			p->v.y -= weight/2;
+		}
+		/* Move bottom inner corner points along NW/SE diagonal */
+		if (p->prev->v.y > p->v.y && p->v.y < p->next->v.y &&
+		    p->prev->v.x < p->v.x && p->v.x < p->next->v.x) {
+			p->v.x -= weight/2;
+			p->v.y += weight/2;
+		}
+	}
+}
+
 static void
 blackpixel(int x, int y, int bl, int br, int tr, int tl)
 {
@@ -1916,6 +1955,7 @@ dochar(char const data[YSIZE], unsigned flags)
 		}
 	}
 	clean_path();
+	adjust_weight();
 	emit_path();
 }