tessellatedquadmesh.cpp Example File

tessellation-modes/tessellatedquadmesh.cpp

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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"