From aafcab1e7237d3ccbc80945eb8379a985d567a53 Mon Sep 17 00:00:00 2001
From: Samuel Fadel <samuelfadel@gmail.com>
Date: Mon, 18 May 2015 13:10:34 -0300
Subject: ForceScheme now (hopefully) does not produce NaNs. Removed the Glyph
 class and placed all scatterplot drawing code inside the Scatterplot class.

---
 scatterplot.cpp | 94 ++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 77 insertions(+), 17 deletions(-)

(limited to 'scatterplot.cpp')

diff --git a/scatterplot.cpp b/scatterplot.cpp
index e775661..b5e8261 100644
--- a/scatterplot.cpp
+++ b/scatterplot.cpp
@@ -1,11 +1,16 @@
 #include "scatterplot.h"
 
+#include <cmath>
 #include <cstdio>
-#include "glyph.h"
 #include <QSGNode>
+#include <QSGGeometry>
 #include <QSGGeometryNode>
+#include <QSGMaterial>
+#include <QSGFlatColorMaterial>
 
-const int GLYPH_SIZE = 10;
+const int GLYPH_SIZE = 4;
+const float PADDING = 5;
+const float PI = 3.1415f;
 
 Scatterplot::Scatterplot()
 {
@@ -22,38 +27,93 @@ void Scatterplot::setData(const arma::mat &data)
         return;
 
     m_data = data;
-    qreal xmin = m_data.col(0).min(),
-          xmax = m_data.col(0).max(),
-          ymin = m_data.col(1).min(),
-          ymax = m_data.col(1).max();
+    update();
+}
 
-    for (arma::uword i = 0; i < m_data.n_rows; i++) {
-        arma::rowvec row = m_data.row(i);
+int calculateCircleVertexCount(qreal radius)
+{
+    // 10 * sqrt(r) \approx 2*pi / acos(1 - 1 / (4*r))
+    return (int) (10.0 * sqrt(radius));
+}
+
+void updateCircleGeometry(QSGGeometry *geometry, float size, float cx, float cy)
+{
+    int vertexCount = geometry->vertexCount();
 
-        Glyph *glyph = new Glyph();
+    float theta = 2 * PI / float(vertexCount);
+    float c = cosf(theta);
+    float s = sinf(theta);
+    float x = size / 2;
+    float y = 0;
 
-        glyph->setSize(5);
-        glyph->setX((row[0] - xmin) / (xmax - xmin) * width());
-        glyph->setY((row[1] - ymin) / (ymax - ymin) * height());
+    QSGGeometry::Point2D *vertexData = geometry->vertexDataAsPoint2D();
+    for (int i = 0; i < vertexCount; i++) {
+        vertexData[i].set(x + cx, y + cy);
 
-        glyph->setParent(this);
+        float t = x;
+        x = c*x - s*y;
+        y = s*t + c*y;
     }
+}
 
-    update();
+void updateSquareGeometry(QSGGeometry *geometry, float size, float cx, float cy)
+{
+    float r = size / 2;
+    QSGGeometry::Point2D *vertexData = geometry->vertexDataAsPoint2D();
+    vertexData[0].set(cx - r, cy - r);
+    vertexData[1].set(cx + r, cy - r);
+    vertexData[2].set(cx + r, cy + r);
+    vertexData[3].set(cx - r, cy + r);
 }
 
 QSGNode *Scatterplot::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
 {
     QSGNode *node = 0;
+    QSGGeometryNode *childNode = 0;
+    QSGGeometry *geometry = 0;
+    QSGFlatColorMaterial *material = 0;
+    int vertexCount = calculateCircleVertexCount(GLYPH_SIZE / 2);
+    qreal xmin = m_data.col(0).min(),
+          xmax = m_data.col(0).max(),
+          ymin = m_data.col(1).min(),
+          ymax = m_data.col(1).max(),
+          x, y;
 
     if (!oldNode) {
         node = new QSGNode;
-        for (QObjectList::const_iterator it = children().begin(); it != children().end(); it++)
-            node->appendChildNode(static_cast<Glyph *>(*it)->updatePaintNode(0, 0));
+        for (arma::uword i = 0; i < m_data.n_rows; i++) {
+            arma::rowvec row = m_data.row(i);
+            x = (row[0] - xmin) / (xmax - xmin) * width();
+            y = (row[1] - ymin) / (ymax - ymin) * height();
+
+            childNode = new QSGGeometryNode;
+
+            geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount);
+            geometry->setDrawingMode(GL_POLYGON);
+            childNode->setGeometry(geometry);
+            childNode->setFlag(QSGNode::OwnsGeometry);
+
+            material = new QSGFlatColorMaterial;
+            material->setColor(QColor());
+            childNode->setMaterial(material);
+            childNode->setFlag(QSGNode::OwnsMaterial);
+
+            node->appendChildNode(childNode);
+        }
     } else {
-        node = static_cast<QSGNode *>(oldNode);
+        node = oldNode;
     }
 
+    childNode = static_cast<QSGGeometryNode *>(node->firstChild());
+    for (arma::uword i = 0; i < m_data.n_rows; i++) {
+        arma::rowvec row = m_data.row(i);
+        x = (row[0] - xmin) / (xmax - xmin) * width();
+        y = (row[1] - ymin) / (ymax - ymin) * height();
+
+        geometry = childNode->geometry();
+        updateCircleGeometry(geometry, GLYPH_SIZE, x, y);
+        childNode = static_cast<QSGGeometryNode *>(childNode->nextSibling());
+    }
     node->markDirty(QSGNode::DirtyGeometry);
 
     return node;
-- 
cgit v1.2.3