Updated Scatteplot's drawing code.

- All glyphs use the same geometry, placement is done via affine transforms
- Geometry memory handled using unique_ptr
- Added outline to each glyph, avoiding color issues with the background

1 files changed, 37 insertions, 15 deletions

diff --git a/scatterplot.cpp b/scatterplot.cpp
index 0a252e1..ce8f590 100644
--- a/scatterplot.cpp
+++ b/scatterplot.cpp
@@ -1,10 +1,14 @@
 #include "scatterplot.h"
 
+#include <QMatrix4x4>
 #include <cmath>
 
 static const qreal GLYPH_OPACITY = 0.4;
 static const qreal GLYPH_OPACITY_SELECTED = 1.0;
-static const QColor SELECTION_COLOR(QColor(128, 128, 128, 96));
+
+static const QColor OUTLINE_COLOR(0, 0, 0);
+static const QColor SELECTION_COLOR(128, 128, 128, 96);
+
 static const int GLYPH_SIZE = 8;
 static const float PADDING = 10;
 static const float PI = 3.1415f;
@@ -123,22 +127,40 @@ QSGNode *Scatterplot::createGlyphNodeTree()
     QSGNode *node = new QSGNode;
     int vertexCount = calculateCircleVertexCount(GLYPH_SIZE / 2);
 
-    for (arma::uword i = 0; i < m_xy.n_rows; i++) {
-        QSGGeometryNode *glyphNode = new QSGGeometryNode;
+    m_glyphGeometryPtr.reset(new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount));
+    QSGGeometry *glyphGeometry = m_glyphGeometryPtr.get();
+    glyphGeometry->setDrawingMode(GL_POLYGON);
+    updateCircleGeometry(glyphGeometry, GLYPH_SIZE, 0, 0);
+
+    m_glyphOutlineGeometryPtr.reset(new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount));
+    QSGGeometry *glyphOutlineGeometry = m_glyphOutlineGeometryPtr.get();
+    glyphOutlineGeometry->setDrawingMode(GL_LINE_LOOP);
+    updateCircleGeometry(glyphOutlineGeometry, GLYPH_SIZE + 1, 0, 0);
 
-        QSGGeometry *geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount);
-        geometry->setDrawingMode(GL_POLYGON);
-        glyphNode->setGeometry(geometry);
-        glyphNode->setFlag(QSGNode::OwnsGeometry);
+    for (arma::uword i = 0; i < m_xy.n_rows; i++) {
+        QSGGeometryNode *glyphOutlineNode = new QSGGeometryNode;
+        glyphOutlineNode->setGeometry(glyphOutlineGeometry);
 
         QSGFlatColorMaterial *material = new QSGFlatColorMaterial;
+        material->setColor(OUTLINE_COLOR);
+        glyphOutlineNode->setMaterial(material);
+        glyphOutlineNode->setFlag(QSGNode::OwnsMaterial);
+
+        QSGGeometryNode *glyphNode = new QSGGeometryNode;
+        glyphNode->setGeometry(glyphGeometry);
+
+        material = new QSGFlatColorMaterial;
         material->setColor(QColor());
         glyphNode->setMaterial(material);
         glyphNode->setFlag(QSGNode::OwnsMaterial);
 
+        QSGTransformNode *transformNode = new QSGTransformNode;
+        transformNode->appendChildNode(glyphNode);
+        transformNode->appendChildNode(glyphOutlineNode);
+
         // Place the glyph geometry node under an opacity node
         QSGOpacityNode *glyphOpacityNode = new QSGOpacityNode;
-        glyphOpacityNode->appendChildNode(glyphNode);
+        glyphOpacityNode->appendChildNode(transformNode);
         node->appendChildNode(glyphOpacityNode);
     }
 
@@ -150,7 +172,8 @@ QSGNode *Scatterplot::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
     if (m_xy.n_rows < 1)
         return 0;
 
-    qreal x, y, tx, ty, moveTranslationF;
+    QMatrix4x4 matrix;
+    qreal tx, ty, moveTranslationF;
 
     QSGNode *root = 0;
     if (!oldNode) {
@@ -173,16 +196,15 @@ QSGNode *Scatterplot::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
         QSGOpacityNode *glyphOpacityNode = static_cast<QSGOpacityNode *>(node);
         glyphOpacityNode->setOpacity(isSelected ? GLYPH_OPACITY_SELECTED : GLYPH_OPACITY);
 
-        QSGGeometryNode *glyphNode = static_cast<QSGGeometryNode *>(node->firstChild());
+        QSGTransformNode *transformNode = static_cast<QSGTransformNode *>(node->firstChild());
         if (m_shouldUpdateGeometry) {
-            QSGGeometry *geometry = glyphNode->geometry();
             moveTranslationF = isSelected ? 1.0 : 0.0;
-            x = fromDataXToScreenX(row[0]) + tx * moveTranslationF;
-            y = fromDataYToScreenY(row[1]) + ty * moveTranslationF;
-            updateCircleGeometry(geometry, GLYPH_SIZE, x, y);
-            glyphNode->markDirty(QSGNode::DirtyGeometry);
+            matrix(0, 3) = fromDataXToScreenX(row[0]) + tx * moveTranslationF;
+            matrix(1, 3) = fromDataYToScreenY(row[1]) + ty * moveTranslationF;
+            transformNode->setMatrix(matrix);
         }
         if (m_shouldUpdateMaterials) {
+            QSGGeometryNode *glyphNode = static_cast<QSGGeometryNode *>(transformNode->firstChild());
             QSGFlatColorMaterial *material = static_cast<QSGFlatColorMaterial *>(glyphNode->material());
             material->setColor(m_colorScale->color(m_colorData[i]));
             glyphNode->setMaterial(material);