From 4c066a82962a9a0634dcfe0a305de7b2a4cacc5b Mon Sep 17 00:00:00 2001
From: Samuel Fadel <samuelfadel@gmail.com>
Date: Sat, 16 Jan 2016 20:55:45 +0100
Subject: Added the Colormap component.

* The Colormap component is a simple rect with a texture mapped
  that displays a ColorScale with a fixed number of samples. This
  number of samples is exported as a member const, which is used
  on other components (such as VoronoiSplat).
* The texture mapping is reflecting the colormap lookup used in
  VoronoiSplat.
* The ColorScale class now has a method for sampling the color
  scale and outputs the samples to iterator-style objects,
  providing easy intergration with existing code.
---
 colormap.cpp | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 colormap.cpp

(limited to 'colormap.cpp')

diff --git a/colormap.cpp b/colormap.cpp
new file mode 100644
index 0000000..545151f
--- /dev/null
+++ b/colormap.cpp
@@ -0,0 +1,113 @@
+#include "colormap.h"
+
+#include <QOpenGLFunctions>
+#include <QSGSimpleTextureNode>
+
+class ColormapTexture
+    : public QSGDynamicTexture
+{
+public:
+    ColormapTexture(const std::vector<float> *cmap);
+    ~ColormapTexture();
+
+    bool hasAlphaChannel() const { return false; }
+    bool hasMipmaps() const { return false; }
+    void bind();
+    bool updateTexture();
+
+    int textureId() const { return m_texture; }
+    QSize textureSize() const { return m_size; }
+
+private:
+    QOpenGLFunctions gl;
+
+    QSize m_size;
+    GLuint m_texture;
+    const std::vector<float> *m_cmap;
+};
+
+ColormapTexture::ColormapTexture(const std::vector<float> *cmap)
+    : gl(QOpenGLContext::currentContext())
+    , m_size(Colormap::SAMPLES, 1)
+    , m_cmap(cmap)
+{
+    // Setup OpenGL texture
+    gl.glGenTextures(1, &m_texture);
+    gl.glBindTexture(GL_TEXTURE_2D, m_texture);
+    gl.glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, m_size.width(), m_size.height(),
+            0, GL_RGB, GL_FLOAT, 0);
+    gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+}
+
+ColormapTexture::~ColormapTexture()
+{
+    gl.glDeleteTextures(1, &m_texture);
+}
+
+void ColormapTexture::bind()
+{
+    gl.glBindTexture(GL_TEXTURE_2D, m_texture);
+}
+
+bool ColormapTexture::updateTexture()
+{
+    gl.glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_size.width(), m_size.height(),
+            GL_RGB, GL_FLOAT, m_cmap->data());
+    return true;
+}
+
+Colormap::Colormap(QQuickItem *parent)
+    : QQuickItem(parent)
+    , m_texture(0)
+    , m_shouldUpdateTexture(false)
+    , m_cmap(3*SAMPLES)
+{
+    setFlag(QQuickItem::ItemHasContents);
+}
+
+Colormap::~Colormap()
+{
+    if (m_texture) {
+        delete m_texture;
+    }
+}
+
+
+void Colormap::setColorScale(const ColorScale &scale)
+{
+    scale.sample(SAMPLES, m_cmap.begin());
+    emit colorScaleChanged(scale);
+
+    m_shouldUpdateTexture = true;
+    update();
+}
+
+QSGNode *Colormap::newSceneGraph()
+{
+    QSGSimpleTextureNode *node = new QSGSimpleTextureNode;
+    m_texture = new ColormapTexture(&m_cmap);
+
+    node->setTexture(m_texture);
+    node->setOwnsTexture(false);
+
+    const QSize &texSize = m_texture->textureSize();
+    node->setSourceRect(0, 0, texSize.width(), texSize.height());
+
+    return node;
+}
+
+QSGNode *Colormap::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
+{
+    QSGNode *root = oldNode ? oldNode : newSceneGraph();
+
+    QSGSimpleTextureNode *node = static_cast<QSGSimpleTextureNode *>(root);
+    node->setRect(x(), y(), width(), height());
+
+    if (m_shouldUpdateTexture) {
+        m_texture->updateTexture();
+        m_shouldUpdateTexture = false;
+    }
+
+    return root;
+}
-- 
cgit v1.2.3