From: Joe Wreschnig <joe.wreschnig@gmail.com>
Date: Wed, 17 Sep 2014 21:34:13 +0000 (+0200)
Subject: Disable DPR > 1 on Safari due to bugs and performance issues.
X-Git-Url: https://git.yukkurigames.com/?a=commitdiff_plain;h=0fcb2653386058a7206bb31920834f66fabf3e4e;p=pwl6.git

Disable DPR > 1 on Safari due to bugs and performance issues.
---

diff --git a/src/yuu/core.js b/src/yuu/core.js
index cbeb2a0..24e3f2b 100644
--- a/src/yuu/core.js
+++ b/src/yuu/core.js
@@ -7,6 +7,9 @@
 (function (yuu) {
     "use strict";
 
+    yuu.isSafari = function (ua) {
+        return /^((?!chrome).)*safari/i.test(ua || navigator.userAgent);
+    };
 
     yuu.require = function (m) {
         try { return require(m); }
diff --git a/src/yuu/gfx.js b/src/yuu/gfx.js
index 2c3088e..3765aaa 100644
--- a/src/yuu/gfx.js
+++ b/src/yuu/gfx.js
@@ -12,7 +12,22 @@
     var gl;
     var canvas;
 
-    var dpr = yuu.DPR = this.devicePixelRatio || 1;
+    // Safari on OS X has issues with DPR != 1 where the backbuffer
+    // scales down, then back up. I'm pretty sure this is not a
+    // problem with this code, because I see similar artifacting on
+    // most demos, e.g.
+    // https://www.khronos.org/registry/webgl/sdk/demos/google/shiny-teapot/index.html
+    //
+    // With DPR = 1 this presumably still happens but the negative
+    // effect is lessened.
+    //
+    // Safari on iOS does _not_ have this problem (another reason why
+    // I suspect it's a bug in Safari and not this code), but reducing
+    // fragment count by 75% is generally a good idea on these devices
+    // anyway.
+    var dpr = yuu.DPR = !yuu.isSafari()
+        ? (this.devicePixelRatio || 1)
+        : 1;
 
     yT.defineProperty(Int8Array.prototype, "GL_TYPE", 0x1400);
     yT.defineProperty(Uint8Array.prototype, "GL_TYPE", 0x1401);