Qt Quick 3D - Custom Morphing Animation

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#include "morphgeometry.h" #include <qmath.h> struct Vertex { QVector3D position; QVector3D normal; QVector3D targetPosition; QVector3D targetNormal; }; Q_STATIC_ASSERT((sizeof(Vertex)/16)*16 == sizeof(Vertex)); // must be 4-float aligned MorphGeometry::MorphGeometry(QQuick3DObject *parent) : QQuick3DGeometry(parent) { updateData(); } void MorphGeometry::setGridSize(int gridSize) { if (m_gridSize == gridSize) return; m_gridSize = gridSize; emit gridSizeChanged(); updateData(); update(); } void MorphGeometry::updateData() { clear(); calculateGeometry(); addAttribute(QQuick3DGeometry::Attribute::PositionSemantic, 0, QQuick3DGeometry::Attribute::ComponentType::F32Type); addAttribute(QQuick3DGeometry::Attribute::NormalSemantic, 3 * sizeof(float), QQuick3DGeometry::Attribute::ComponentType::F32Type); addAttribute(QQuick3DGeometry::Attribute::TargetPositionSemantic, 6 * sizeof(float), QQuick3DGeometry::Attribute::ComponentType::F32Type); addAttribute(QQuick3DGeometry::Attribute::TargetNormalSemantic, 9 * sizeof(float), QQuick3DGeometry::Attribute::ComponentType::F32Type); addAttribute(QQuick3DGeometry::Attribute::IndexSemantic, 0, QQuick3DGeometry::Attribute::ComponentType::U32Type); const int numVertexes = m_positions.size(); m_vertexBuffer.resize(numVertexes * sizeof(Vertex)); Vertex *vert = reinterpret_cast<Vertex *>(m_vertexBuffer.data()); for (int i = 0; i < numVertexes; ++i) { Vertex &v = vert[i]; v.position = m_positions[i]; v.normal = m_normals[i]; v.targetPosition = m_targetPositions[i]; v.targetNormal = m_targetNormals[i]; } setStride(sizeof(Vertex)); setVertexData(m_vertexBuffer); setPrimitiveType(QQuick3DGeometry::PrimitiveType::Triangles); m_indexBuffer = QByteArray(reinterpret_cast<char *>(m_indexes.data()), m_indexes.size() * sizeof(quint32)); setIndexData(m_indexBuffer); } void MorphGeometry::calculateGeometry() { float dw = 10.0; // width/2 float dh = 10.0; int iw = m_gridSize; int ih = m_gridSize; float wf = dw * 2 / iw; //factor grid coord => position float hf = dh * 2 / ih; m_positions.clear(); m_indexes.clear(); m_targetPositions.clear(); m_targetNormals.clear(); // We construct a rectangular grid of iw times ih vertices; // ix and iy are indices into the grid. x, y, and z are the spatial // coordinates we calculate for each vertex. tx, ty, and tz are the // coordinates for the morph target. for (int iy = 0; iy < ih; ++iy) { for (int ix = 0; ix < iw; ++ix) { float x = ix * wf - dw; float z = iy * hf - dh; // The base shape is a cosine wave, and the corresponding normal // vectors are calculated from the partial derivatives. float y = 2 * qCos(x) + 3.0; QVector3D normal{2 * qSin(x), 2, 0}; float tx = x * 1.2; float tz = z * 1.2; constexpr float R = 16; QVector3D targetPosition; QVector3D targetNormal; // The morph target shape is a hemisphere. Therefore we don't have // to do complex math to calculate the normal vector, since all vectors // from the center are normal to the surface of a sphere. if (tx*tx + tz*tz < R*R) { float ty = 0.4f * qSqrt(R*R - tx*tx - tz*tz); targetPosition = {tx, ty, tz}; targetNormal = targetPosition; } else { targetPosition = {tx, -3, tz}; targetNormal = {0, 1, 0}; } // Finally, we make the outside edges of the shapes vertical, so they look nicer. if (ix == 0 || iy == 0 || ix == iw-1 || iy == ih-1) { int iix = qMin(iw-2, qMax(1, ix)); int iiy = qMin(ih-2, qMax(1, iy)); x = iix * wf - dw; z = iiy * hf - dh; y = -3.0; targetPosition.setY(-3); } if (iy >= ih-2) normal = {0, 0, 1}; else if (iy <= 1) normal = {0, 0, -1}; m_positions.append({x, y, z}); m_normals.append(normal.normalized()); m_targetPositions.append(targetPosition); m_targetNormals.append(targetNormal.normalized()); } } for (int ix = 0; ix < iw - 1; ++ix) { for (int iy = 0; iy < ih - 1; ++iy) { int idx = ix + iy * ih; m_indexes << idx << idx + iw << idx + iw + 1 << idx << idx + iw + 1 << idx + 1; } } }