Qt 5.6 | Qt 3D | Qt 3D: Tessellation Modes QML Example | tessellatedquadmesh.cpp Example File

Qt 5.6.3 Reference Documentation

# tessellatedquadmesh.cpp Example File

tessellation-modes/tessellatedquadmesh.cpp

      /****************************************************************************
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      ** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
      ** Contact: http://www.qt-project.org/legal
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      #include "tessellatedquadmesh.h"

      #include <Qt3DRender/qattribute.h>
      #include <Qt3DRender/qbuffer.h>
      #include <Qt3DRender/qgeometry.h>

      class TessellatedGeometry : public Qt3DRender::QGeometry
      {
          Q_OBJECT
      public:
          TessellatedGeometry(Qt3DCore::QNode *parent = Q_NULLPTR)
              : Qt3DRender::QGeometry(parent)
              , m_positionAttribute(new Qt3DRender::QAttribute(this))
              , m_vertexBuffer(new Qt3DRender::QBuffer(Qt3DRender::QBuffer::VertexBuffer, this))
          {
              const float positionData[] = {
                  -0.8f, -0.8f, 0.0f,
                   0.8f, -0.8f, 0.0f,
                   0.8f,  0.8f, 0.0f,
                  -0.8f,  0.8f, 0.0f
              };

              const int nVerts = 4;
              const int size = nVerts * 3 * sizeof(float);
              QByteArray positionBytes;
              positionBytes.resize(size);
              memcpy(positionBytes.data(), positionData, size);

              m_vertexBuffer->setData(positionBytes);

              m_positionAttribute->setName(Qt3DRender::QAttribute::defaultPositionAttributeName());
              m_positionAttribute->setDataType(Qt3DRender::QAttribute::Float);
              m_positionAttribute->setDataSize(3);
              m_positionAttribute->setCount(nVerts);
              m_positionAttribute->setByteStride(3 * sizeof(float));
              m_positionAttribute->setBuffer(m_vertexBuffer);

              setVerticesPerPatch(4);
              addAttribute(m_positionAttribute);
          }

      private:
          Qt3DRender::QAttribute *m_positionAttribute;
          Qt3DRender::QBuffer *m_vertexBuffer;
      };

      TessellatedQuadMesh::TessellatedQuadMesh(Qt3DCore::QNode *parent)
          : Qt3DRender::QGeometryRenderer(parent)
      {
          setPrimitiveType(Qt3DRender::QGeometryRenderer::Patches);
          setGeometry(new TessellatedGeometry(this));
      }

      TessellatedQuadMesh::~TessellatedQuadMesh()
      {
          QNode::cleanup();
      }

      #include "tessellatedquadmesh.moc"