From aeccd2b772b5eb65230f44fe8be060a09e45a2d1 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Mon, 22 Jan 2018 14:05:35 +0100
Subject: [PATCH] Add new animation class.

---
 src/ActivityAnimation.cpp | 48 +++++++++++++++++++++++++++++++++++++++
 src/ActivityAnimation.hpp | 20 ++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 src/ActivityAnimation.cpp
 create mode 100644 src/ActivityAnimation.hpp

diff --git a/src/ActivityAnimation.cpp b/src/ActivityAnimation.cpp
new file mode 100644
index 0000000..c286aaf
--- /dev/null
+++ b/src/ActivityAnimation.cpp
@@ -0,0 +1,48 @@
+#include <cmath>
+#include <cstring>
+#include <random>
+#include <GL/gl.h>
+#include "ActivityAnimation.hpp"
+#include "utils.hpp"
+
+using namespace fmri;
+
+static inline float correct_timescale(float original)
+{
+    float ignore;
+    return std::modf(original, &ignore);
+}
+
+ActivityAnimation::ActivityAnimation(std::size_t count, const float *aPos, const float *bPos, const float xDist) :
+        bufferLength(3 * count),
+        startingPos(new float[bufferLength]),
+        delta(new float[bufferLength]),
+        offset(new float[count])
+{
+    memcpy(startingPos.get(), aPos, sizeof(aPos[0]) * bufferLength);
+    for (int i = 0; i < bufferLength; ++i) {
+        delta[i] = bPos[i] - aPos[i];
+    }
+
+    auto& random = rng();
+    std::uniform_real_distribution<float> rd;
+    for (int i = 0; i < count; ++i) {
+        offset[i] = rd(random);
+        delta[3 * i] += xDist;
+    }
+}
+
+void ActivityAnimation::draw(float timeScale) const
+{
+    std::unique_ptr<float[]> vertexBuffer(new float[bufferLength]);
+
+    for (auto i = 0; i < bufferLength; ++i) {
+        vertexBuffer[i] = startingPos[i] + correct_timescale(offset[i/3] + timeScale) * delta[i];
+    }
+
+    glColor3f(1, 1, 1);
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glVertexPointer(3, GL_FLOAT, 0, vertexBuffer.get());
+    glDrawArrays(GL_POINTS, bufferLength / 3, bufferLength);
+    glDisableClientState(GL_VERTEX_ARRAY);
+}
diff --git a/src/ActivityAnimation.hpp b/src/ActivityAnimation.hpp
new file mode 100644
index 0000000..bad3051
--- /dev/null
+++ b/src/ActivityAnimation.hpp
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstddef>
+#include <memory>
+
+namespace fmri
+{
+    class ActivityAnimation
+    {
+    public:
+        ActivityAnimation(std::size_t count, const float* aPos, const float* bPos, const float xDist);
+        void draw(float timeScale) const;
+
+    private:
+        std::size_t bufferLength;
+        std::unique_ptr<float[]> startingPos;
+        std::unique_ptr<float[]> delta;
+        std::unique_ptr<float[]> offset;
+    };
+}
\ No newline at end of file