From 9f8efe71fab174307ad4404ad4ab0eb1f505fa4e Mon Sep 17 00:00:00 2001
From: Hakim El Hattab <hakim.elhattab@gmail.com>
Date: Mon, 1 Aug 2016 09:15:34 +0200
Subject: [PATCH] none/fade/slide transitions use flat transform style,
 prevents blurred content #1002

---
 css/reveal.css  | 27 +++++++++++++++++++++++----
 css/reveal.scss | 12 +++++++++++-
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/css/reveal.css b/css/reveal.css
index 778076e00fa..fae812332ac 100644
--- a/css/reveal.css
+++ b/css/reveal.css
@@ -341,8 +341,8 @@ body {
   width: 100%;
   padding: 20px 0px;
   z-index: 10;
-  -webkit-transform-style: preserve-3d;
-          transform-style: preserve-3d;
+  -webkit-transform-style: flat;
+          transform-style: flat;
   -webkit-transition: -webkit-transform-origin 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), -webkit-transform 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), visibility 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), opacity 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985);
           transition: transform-origin 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), transform 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), visibility 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985), opacity 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
 
@@ -463,6 +463,11 @@ body {
  * CONVEX TRANSITION
  * Aliased 'default' for backwards compatibility
  *********************************************/
+.reveal .slides section[data-transition=default],
+.reveal.default .slides section:not([data-transition]) {
+  -webkit-transform-style: preserve-3d;
+          transform-style: preserve-3d; }
+
 .reveal .slides > section[data-transition=default].past,
 .reveal .slides > section[data-transition~=default-out].past,
 .reveal.default .slides > section:not([data-transition]).past {
@@ -487,6 +492,11 @@ body {
   -webkit-transform: translate3d(0, 300px, 0) rotateX(-70deg) translate3d(0, 300px, 0);
           transform: translate3d(0, 300px, 0) rotateX(-70deg) translate3d(0, 300px, 0); }
 
+.reveal .slides section[data-transition=convex],
+.reveal.convex .slides section:not([data-transition]) {
+  -webkit-transform-style: preserve-3d;
+          transform-style: preserve-3d; }
+
 .reveal .slides > section[data-transition=convex].past,
 .reveal .slides > section[data-transition~=convex-out].past,
 .reveal.convex .slides > section:not([data-transition]).past {
@@ -514,6 +524,11 @@ body {
 /*********************************************
  * CONCAVE TRANSITION
  *********************************************/
+.reveal .slides section[data-transition=concave],
+.reveal.concave .slides section:not([data-transition]) {
+  -webkit-transform-style: preserve-3d;
+          transform-style: preserve-3d; }
+
 .reveal .slides > section[data-transition=concave].past,
 .reveal .slides > section[data-transition~=concave-out].past,
 .reveal.concave .slides > section:not([data-transition]).past {
@@ -584,7 +599,9 @@ body {
   min-height: 700px;
   -webkit-backface-visibility: hidden;
           backface-visibility: hidden;
-  box-sizing: border-box; }
+  box-sizing: border-box;
+  -webkit-transform-style: preserve-3d;
+          transform-style: preserve-3d; }
 
 .reveal.center.cube .slides section {
   min-height: 0; }
@@ -657,7 +674,9 @@ body {
 .reveal.page .slides section {
   padding: 30px;
   min-height: 700px;
-  box-sizing: border-box; }
+  box-sizing: border-box;
+  -webkit-transform-style: preserve-3d;
+          transform-style: preserve-3d; }
 
 .reveal.page .slides section.past {
   z-index: 12; }
diff --git a/css/reveal.scss b/css/reveal.scss
index 9045428bc7b..c888a2751d0 100644
--- a/css/reveal.scss
+++ b/css/reveal.scss
@@ -408,7 +408,7 @@ body {
 	padding: 20px 0px;
 
 	z-index: 10;
-	transform-style: preserve-3d;
+	transform-style: flat;
 	transition: transform-origin 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985),
 				transform 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985),
 				visibility 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985),
@@ -539,6 +539,10 @@ body {
  *********************************************/
 
 @each $stylename in default, convex {
+	@include transition-global(#{$stylename}) {
+		transform-style: preserve-3d;
+	}
+
 	@include transition-horizontal-past(#{$stylename}) {
 		transform: translate3d(-100%, 0, 0) rotateY(-90deg) translate3d(-100%, 0, 0);
 	}
@@ -557,6 +561,10 @@ body {
  * CONCAVE TRANSITION
  *********************************************/
 
+@include transition-global(concave) {
+	transform-style: preserve-3d;
+}
+
 @include transition-horizontal-past(concave) {
 	transform: translate3d(-100%, 0, 0) rotateY(90deg) translate3d(-100%, 0, 0);
 }
@@ -607,6 +615,7 @@ body {
 	min-height: 700px;
 	backface-visibility: hidden;
 	box-sizing: border-box;
+	transform-style: preserve-3d;
 }
 	.reveal.center.cube .slides section {
 		min-height: 0;
@@ -678,6 +687,7 @@ body {
 	padding: 30px;
 	min-height: 700px;
 	box-sizing: border-box;
+	transform-style: preserve-3d;
 }
 	.reveal.page .slides section.past {
 		z-index: 12;