From 02ce2f4becc513218afecd8cfdb0fc31227389fc Mon Sep 17 00:00:00 2001
From: Frederic Junod <frederic.junod@camptocamp.com>
Date: Tue, 4 Jun 2019 13:23:12 +0200
Subject: [PATCH 1/2] Use compose function from ol/transform

---
 src/ol/webgl/Helper.js | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/ol/webgl/Helper.js b/src/ol/webgl/Helper.js
index 1b03a5fa0d..d9c2c8d638 100644
--- a/src/ol/webgl/Helper.js
+++ b/src/ol/webgl/Helper.js
@@ -10,11 +10,11 @@ import {clear} from '../obj.js';
 import {ARRAY_BUFFER, ELEMENT_ARRAY_BUFFER, TEXTURE_2D, TEXTURE_WRAP_S, TEXTURE_WRAP_T} from '../webgl.js';
 import ContextEventType from '../webgl/ContextEventType.js';
 import {
+  compose as composeTransform,
   create as createTransform,
   reset as resetTransform,
   rotate as rotateTransform,
-  scale as scaleTransform,
-  translate as translateTransform
+  scale as scaleTransform
 } from '../transform.js';
 import {create, fromTransform} from '../vec/mat4.js';
 import WebGLPostProcessingPass from './PostProcessingPass.js';
@@ -691,10 +691,12 @@ class WebGLHelper extends Disposable {
     const center = frameState.viewState.center;
 
     resetTransform(transform);
-    scaleTransform(transform, 2 / (resolution * size[0]), 2 / (resolution * size[1]));
-    rotateTransform(transform, -rotation);
-    translateTransform(transform, -center[0], -center[1]);
-
+    composeTransform(transform,
+      0, 0,
+      2 / (resolution * size[0]), 2 / (resolution * size[1]),
+      -rotation,
+      -center[0], -center[1]
+    );
     return transform;
   }
 

From 91d49b26b5e06adf822aa68368b53a9708479294 Mon Sep 17 00:00:00 2001
From: Frederic Junod <frederic.junod@camptocamp.com>
Date: Tue, 4 Jun 2019 14:00:39 +0200
Subject: [PATCH 2/2] Round the transform values in makeProjectionTransform
 test

---
 test/spec/ol/webgl/helper.test.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/test/spec/ol/webgl/helper.test.js b/test/spec/ol/webgl/helper.test.js
index 39fb1a2d68..c474941c60 100644
--- a/test/spec/ol/webgl/helper.test.js
+++ b/test/spec/ol/webgl/helper.test.js
@@ -213,7 +213,10 @@ describe('ol.webgl.WebGLHelper', function() {
         scaleTransform(expected, scaleX, scaleY);
         rotateTransform(expected, -frameState.viewState.rotation);
         translateTransform(expected, -frameState.viewState.center[0], -frameState.viewState.center[1]);
-        expect(h.makeProjectionTransform(frameState, given)).to.eql(expected);
+
+        h.makeProjectionTransform(frameState, given);
+
+        expect(given.map(val => val.toFixed(15))).to.eql(expected.map(val => val.toFixed(15)));
       });
     });