Attachment 11758 Details for Bug 7245 – Correct the mitre limit derivation

[patch] Correct the mitre limit derivation

0001-cairo-path-stroke-Correct-the-mitre-limit-derivati.patch (text/plain), 1.90 KB, created by Chris Wilson on 2007-09-26 03:36:28 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Chris Wilson

Created: 2007-09-26 03:36:28 UTC

Size: 1.90 KB

patch

obsolete

>From af1bdbb198e7fcef6b996bd14168ee4bdde208fa Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Wed, 26 Sep 2007 11:33:10 +0100
>Subject: [PATCH] [cairo-path-stroke] Correct the mitre limit derivation.
>MIME-Version: 1.0
>Content-Type: text/plain; charset=utf-8
>Content-Transfer-Encoding: 8bit
>
>The first identity used in the derivation of the mitre limit is
>incorrect, namely secant(psi/2) â  1/sin(psi/2) but
>secant(psi/2) = 1/cos(psi/2) instead. Update the derivation using the
>identity 2Â·cosÂ²(psi/2) = 1+cos(psi) and arrive at the similar result
>2 <= mlÂ² (1 + in Â· out).
>
>(Fixes https://bugs.freedesktop.org/show_bug.cgi?id=7245.)
>---
> src/cairo-path-stroke.c |   18 +++++++++---------
> 1 files changed, 9 insertions(+), 9 deletions(-)
>
>diff --git a/src/cairo-path-stroke.c b/src/cairo-path-stroke.c
>index d8d989b..1feda9d 100644
>--- a/src/cairo-path-stroke.c
>+++ b/src/cairo-path-stroke.c
>@@ -284,13 +284,13 @@ _cairo_stroker_join (cairo_stroker_t *stroker, cairo_stroke_face_t *in, cairo_st
> 	 *
> 	 * where psi is the angle between in and out
> 	 *
>-	 *				secant(psi/2) = 1/sin(psi/2)
>-	 *	1/sin(psi/2) <= ml
>-	 *	1 <= ml sin(psi/2)
>-	 *	1 <= mlÂ² sinÂ²(psi/2)
>-	 *	2 <= mlÂ² 2 sinÂ²(psi/2)
>-	 *				2Â·sinÂ²(psi/2) = 1-cos(psi)
>-	 *	2 <= mlÂ² (1-cos(psi))
>+	 *				secant(psi/2) = 1/cos(psi/2)
>+	 *	1/cos(psi/2) <= ml
>+	 *	1 <= ml cos(psi/2)
>+	 *	1 <= mlÂ² cosÂ²(psi/2)
>+	 *	2 <= mlÂ² 2 cosÂ²(psi/2)
>+	 *				2Â·cosÂ²(psi/2) = 1+cos(psi)
>+	 *	2 <= mlÂ² (1+cos(psi))
> 	 *
> 	 *				in Â· out = |in| |out| cos (psi)
> 	 *
>@@ -298,10 +298,10 @@ _cairo_stroker_join (cairo_stroker_t *stroker, cairo_stroke_face_t *in, cairo_st
> 	 *
> 	 *				in Â· out = cos (psi)
> 	 *
>-	 *	2 <= mlÂ² (1 - in Â· out)
>+	 *	2 <= mlÂ² (1 + in Â· out)
> 	 *
> 	 */
>-	if (2 <= ml * ml * (1 - in_dot_out)) {
>+	if (2 <= ml * ml * (1 + in_dot_out)) {
> 	    double		x1, y1, x2, y2;
> 	    double		mx, my;
> 	    double		dx1, dx2, dy1, dy2;
>-- 
>1.5.2.5
>

Actions: View | Splinter Review

Attachments on bug 7245: 5928 | 11758

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.