From 76f92964bfccf9106453d4f8771d964c1c9833ea Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Tue, 27 Mar 2018 13:22:52 +0200
Subject: [PATCH] Reduce copying in animation step.

---
 src/fmri/ActivityAnimation.cpp         | 2 +-
 src/fmri/ImageInteractionAnimation.cpp | 2 +-
 src/fmri/PoolingLayerAnimation.cpp     | 2 +-
 src/fmri/utils.cpp                     | 5 +++--
 src/fmri/utils.hpp                     | 2 +-
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/fmri/ActivityAnimation.cpp b/src/fmri/ActivityAnimation.cpp
index e64744e..16605e1 100644
--- a/src/fmri/ActivityAnimation.cpp
+++ b/src/fmri/ActivityAnimation.cpp
@@ -51,7 +51,7 @@ ActivityAnimation::ActivityAnimation(
 
 void ActivityAnimation::draw(float timeScale)
 {
-    const auto vertexBuffer = animate(startingPos, delta, timeScale);
+    const auto &vertexBuffer = animate(startingPos, delta, timeScale);
     glPointSize(5);
 
     glEnableClientState(GL_VERTEX_ARRAY);
diff --git a/src/fmri/ImageInteractionAnimation.cpp b/src/fmri/ImageInteractionAnimation.cpp
index d14e99e..0fba9e7 100644
--- a/src/fmri/ImageInteractionAnimation.cpp
+++ b/src/fmri/ImageInteractionAnimation.cpp
@@ -8,7 +8,7 @@ using namespace fmri;
 
 void ImageInteractionAnimation::draw(float step)
 {
-    auto vertexBuffer = animate(startingPositions, deltas, step);
+    auto &vertexBuffer = animate(startingPositions, deltas, step);
 
     drawImageTiles(vertexBuffer.size() / 3, vertexBuffer.data(), textureCoordinates.data(), texture);
 }
diff --git a/src/fmri/PoolingLayerAnimation.cpp b/src/fmri/PoolingLayerAnimation.cpp
index b26e595..4a09e01 100644
--- a/src/fmri/PoolingLayerAnimation.cpp
+++ b/src/fmri/PoolingLayerAnimation.cpp
@@ -30,7 +30,7 @@ PoolingLayerAnimation::PoolingLayerAnimation(const LayerData &prevData, const La
 
 void PoolingLayerAnimation::draw(float timeStep)
 {
-    auto vertexBuffer = animate(startingPositions, deltas, timeStep);
+    auto& vertexBuffer = animate(startingPositions, deltas, timeStep);
 
     drawImageTiles(vertexBuffer.size() / 3, vertexBuffer.data(), textureCoordinates.data(), original);
 }
diff --git a/src/fmri/utils.cpp b/src/fmri/utils.cpp
index 4b03af8..f16ce36 100644
--- a/src/fmri/utils.cpp
+++ b/src/fmri/utils.cpp
@@ -16,9 +16,10 @@ std::default_random_engine &fmri::rng()
     return rng;
 }
 
-std::vector<float> fmri::animate(const std::vector<float> &start, const std::vector<float> &delta, float time)
+const std::vector<float> & fmri::animate(const std::vector<float> &start, const std::vector<float> &delta, float time)
 {
-    auto vertexBuffer = delta;
+    static std::vector<float> vertexBuffer;
+    vertexBuffer = delta;
     caffe::caffe_scal(vertexBuffer.size(), time, vertexBuffer.data());
     caffe::caffe_add(start.size(), vertexBuffer.data(), start.data(), vertexBuffer.data());
 
diff --git a/src/fmri/utils.hpp b/src/fmri/utils.hpp
index 18e87fd..95cabf3 100644
--- a/src/fmri/utils.hpp
+++ b/src/fmri/utils.hpp
@@ -238,5 +238,5 @@ namespace fmri
      * @param time 0..1 where in the animation are we?
      * @return Resulting list of floats.
      */
-    std::vector<float> animate(const std::vector<float>& start, const std::vector<float>& delta, float time);
+    const std::vector<float> & animate(const std::vector<float> &start, const std::vector<float> &delta, float time);
 }