linenode.cpp Example File

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#include "linenode.h" #include <QtGui/QColor> #include <QtQuick/QSGSimpleMaterial> struct LineMaterial { QColor color; float spread; float size; }; class LineShader : public QSGSimpleMaterialShader<LineMaterial> { QSG_DECLARE_SIMPLE_SHADER(LineShader, LineMaterial) public: LineShader() { setShaderSourceFile(QOpenGLShader::Vertex, ":/scenegraph/graph/shaders/line.vsh"); setShaderSourceFile(QOpenGLShader::Fragment, ":/scenegraph/graph/shaders/line.fsh"); } QList<QByteArray> attributes() const override { return QList<QByteArray>() << "pos" << "t"; } void updateState(const LineMaterial *m, const LineMaterial *) override { program()->setUniformValue(id_color, m->color); program()->setUniformValue(id_spread, m->spread); program()->setUniformValue(id_size, m->size); } void resolveUniforms() override { id_spread = program()->uniformLocation("spread"); id_size = program()->uniformLocation("size"); id_color = program()->uniformLocation("color"); } private: int id_color = -1; int id_spread = -1; int id_size = -1; }; struct LineVertex { float x; float y; float t; inline void set(float xx, float yy, float tt) { x = xx; y = yy; t = tt; } }; static const QSGGeometry::AttributeSet &attributes() { static QSGGeometry::Attribute attr[] = { QSGGeometry::Attribute::create(0, 2, GL_FLOAT, true), QSGGeometry::Attribute::create(1, 1, GL_FLOAT) }; static QSGGeometry::AttributeSet set = { 2, 3 * sizeof(float), attr }; return set; } LineNode::LineNode(float size, float spread, const QColor &color) : m_geometry(attributes(), 0) { setGeometry(&m_geometry); m_geometry.setDrawingMode(GL_TRIANGLE_STRIP); QSGSimpleMaterial<LineMaterial> *m = LineShader::createMaterial(); m->state()->color = color; m->state()->size = size; m->state()->spread = spread; m->setFlag(QSGMaterial::Blending); setMaterial(m); setFlag(OwnsMaterial); } /* * Assumes that samples have values in the range of 0 to 1 and scales them to * the height of bounds. The samples are stretched out horizontally along the * width of the bounds. * * The position of each pair of points is identical, but we use the third value * "t" to shift the point up or down and to add antialiasing. */ void LineNode::updateGeometry(const QRectF &bounds, const QList<qreal> &samples) { m_geometry.allocate(samples.size() * 2); float x = bounds.x(); float y = bounds.y(); float w = bounds.width(); float h = bounds.height(); float dx = w / (samples.size() - 1); LineVertex *v = (LineVertex *) m_geometry.vertexData(); for (int i=0; i<samples.size(); ++i) { v[i*2+0].set(x + dx * i, y + * h, 0); v[i*2+1].set(x + dx * i, y + * h, 1); } markDirty(QSGNode::DirtyGeometry); }

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