Applying Texture on Custom Mesh

[Zee_07]

I want to render texture image (.png) on my material faces consist of custom mesh. Structure is rendering fine but without texture. And I want to render the same image on all faces of Tetrahedron structure. I am very new to openGl so may be its very basic question that I want to know that How engine maps the vertex co-ordinates to texture coordinates (Qt3D c++).

  Window window;// (inherits QWindow)

    Qt3DCore::QAspectEngine engine;
    engine.registerAspect(new Qt3DRender::QRenderAspect());
    Qt3DInput::QInputAspect *input = new Qt3DInput::QInputAspect;
    engine.registerAspect(input);
    QVariantMap data;
    data.insert(QStringLiteral("surface"), QVariant::fromValue(static_cast<QSurface *>(&window)));
    data.insert(QStringLiteral("eventSource"), QVariant::fromValue(&window));
    engine.setData(data);

    // Root entity
    Qt3DCore::QEntity *rootEntity = new Qt3DCore::QEntity();


    // Camera
    Qt3DCore::QCamera *cameraEntity = new Qt3DCore::QCamera(rootEntity);

    cameraEntity->lens()->setPerspectiveProjection(45.0f, 16.0f/9.0f, 0.1f, 1000.0f);
    cameraEntity->setProjectionType(Qt3DCore::QCameraLens::PerspectiveProjection);
    cameraEntity->setAspectRatio(window.width() / window.height());
    cameraEntity->setUpVector(QVector3D(0.0f, 1.0f, -100.0f));
    cameraEntity->setViewCenter(QVector3D(0.0f, 0.5f, 0.0f));
    cameraEntity->setPosition(QVector3D(0.0f, 60.5f, 15.0f));
    input->setCamera(cameraEntity);

    // FrameGraph
    Qt3DRender::QFrameGraph *frameGraph = new Qt3DRender::QFrameGraph();
    Qt3DRender::QForwardRenderer *forwardRenderer = new Qt3DRender::QForwardRenderer();
    forwardRenderer->setClearColor(QColor::fromRgbF(0.1, 0.8, 0.8, 1.0));
    forwardRenderer->setCamera(cameraEntity);
    frameGraph->setActiveFrameGraph(forwardRenderer);
    rootEntity->addComponent(frameGraph);

    // Torus
    LiRenderableEntity *customMeshEntity = new LiRenderableEntity(rootEntity);

    //setting material
    Qt3DRender::QNormalDiffuseSpecularMapMaterial *material = new Qt3DRender::QNormalDiffuseSpecularMapMaterial();

    Qt3DRender::QTextureImage *textureDfImage = new Qt3DRender::QTextureImage();
    textureDfImage->setSource(QUrl(QStringLiteral("qrc:/Glass/metalbarrel/normal_middle_bumps.webp")));
    material->diffuse()->addTextureImage(textureDfImage);
    material->diffuse()->setSize(5,5);

    customMeshEntity->addComponent(material);

    // Custom Mesh (TetraHedron)
    Qt3DRender::QGeometryRenderer *customMeshRenderer = new Qt3DRender::QGeometryRenderer;
    Qt3DRender::QGeometry *customGeometry = new Qt3DRender::QGeometry(customMeshRenderer);

    Qt3DRender::QBuffer *vertexDataBuffer = new Qt3DRender::QBuffer(Qt3DRender::QBuffer::VertexBuffer, customGeometry);
    Qt3DRender::QBuffer *indexDataBuffer = new Qt3DRender::QBuffer(Qt3DRender::QBuffer::IndexBuffer, customGeometry);

    // 4 distinct vertices
    QByteArray vertexBufferData;
    vertexBufferData.resize(4 * (3 + 3 + 2) * sizeof(float));

    // Vertices
    QVector3D v0(-1.0f, 0.9f, -1.0f);
    QVector3D v1(1.0f, 0.9f, -1.0f);
    QVector3D v2(0.0f, 1.9f, 0.0f);
    QVector3D v3(0.0f, 0.9f, 1.0f);

    QVector2D v01(0,0);
    QVector2D v02(0,1);
    QVector2D v03(1,1);
    QVector2D v04(1,0);

    // Faces Normals
    QVector3D n023 = QVector3D::normal(v0, v2, v3);
    QVector3D n012 = QVector3D::normal(v0, v1, v2);
    QVector3D n310 = QVector3D::normal(v3, v1, v0);
    QVector3D n132 = QVector3D::normal(v1, v3, v2);

    // Vector Normals
        QVector3D n0 = QVector3D(n023 + n012 + n310).normalized();
        QVector3D n1 = QVector3D(n132 + n012 + n310).normalized();
        QVector3D n2 = QVector3D(n132 + n012 + n023).normalized();
        QVector3D n3 = QVector3D(n132 + n310 + n023).normalized();

    QVector<QVector3D> vertices = QVector<QVector3D>()
            << v0
            << v1
            << v2
            << v3
            << n023
            << n012
            << n310
            << n132 ;
    QVector<QVector2D> vertices2d = QVector<QVector2D>()
            << v01
            << v02
            << v03
            << v04;

    float *rawVertexArray = reinterpret_cast<float *>(vertexBufferData.data());
    int idx = 0;

    Q_FOREACH (const QVector3D &v, vertices) {
        rawVertexArray[idx++] = v.x();
        rawVertexArray[idx++] = v.y();
        rawVertexArray[idx++] = v.z();
    }
    Q_FOREACH (const QVector2D &v, vertices2d) {
        rawVertexArray[idx++] = v.x();
        rawVertexArray[idx++] = v.y();
    }

    // Indices (12)
    QByteArray indexBufferData;
    indexBufferData.resize(4 * 3 * sizeof(ushort));
    ushort *rawIndexArray = reinterpret_cast<ushort *>(indexBufferData.data());

    // Front
    rawIndexArray[0] = 0;
    rawIndexArray[1] = 1;
    rawIndexArray[2] = 2;
    // Bottom
    rawIndexArray[3] = 3;
    rawIndexArray[4] = 1;
    rawIndexArray[5] = 0;
    // Left
    rawIndexArray[6] = 0;
    rawIndexArray[7] = 2;
    rawIndexArray[8] = 3;
    // Right
    rawIndexArray[9] = 1;
    rawIndexArray[10] = 3;
    rawIndexArray[11] = 2;

    vertexDataBuffer->setData(vertexBufferData);
    indexDataBuffer->setData(indexBufferData);

    // Attributes
    Qt3DRender::QAttribute *positionAttribute = new Qt3DRender::QAttribute();
    positionAttribute->setAttributeType(Qt3DRender::QAttribute::VertexAttribute);
    positionAttribute->setBuffer(vertexDataBuffer);
    positionAttribute->setDataType(Qt3DRender::QAttribute::Float);
    positionAttribute->setDataSize(3);
    positionAttribute->setByteOffset(0);
    positionAttribute->setByteStride(3 * sizeof(float));
    positionAttribute->setCount(4);
    positionAttribute->setName(Qt3DRender::QAttribute::defaultPositionAttributeName());

    Qt3DRender::QAttribute *normalAttribute = new Qt3DRender::QAttribute();
    normalAttribute->setAttributeType(Qt3DRender::QAttribute::VertexAttribute);
    normalAttribute->setBuffer(vertexDataBuffer);
    normalAttribute->setDataType(Qt3DRender::QAttribute::Float);
    normalAttribute->setDataSize(3);
    normalAttribute->setByteOffset(12 * sizeof(float));
    normalAttribute->setByteStride(3 * sizeof(float));
    normalAttribute->setCount(4);
    normalAttribute->setName(Qt3DRender::QAttribute::defaultNormalAttributeName());

    Qt3DRender::QAttribute *indexAttribute = new Qt3DRender::QAttribute();
    indexAttribute->setAttributeType(Qt3DRender::QAttribute::IndexAttribute);
    indexAttribute->setBuffer(indexDataBuffer);
    indexAttribute->setDataType(Qt3DRender::QAttribute::UnsignedShort);
    indexAttribute->setDataSize(1);
    indexAttribute->setByteOffset(0);
    indexAttribute->setByteStride(0);
    indexAttribute->setCount(12);

    Qt3DRender::QAttribute *textureCoordinateAttribute = new Qt3DRender::QAttribute();
    textureCoordinateAttribute->setAttributeType(Qt3DRender::QAttribute::VertexAttribute);
    textureCoordinateAttribute->setBuffer(vertexDataBuffer);
    textureCoordinateAttribute->setDataType(Qt3DRender::QAttribute::Float);
    textureCoordinateAttribute->setDataSize(2);
    textureCoordinateAttribute->setByteOffset(24 * sizeof(float));
    textureCoordinateAttribute->setByteStride(2 * sizeof(float));
    textureCoordinateAttribute->setCount(4);
    textureCoordinateAttribute->setName(Qt3DRender::QAttribute::defaultTextureCoordinateAttributeName());

    customGeometry->addAttribute(positionAttribute);
    customGeometry->addAttribute(normalAttribute);
    customGeometry->addAttribute(indexAttribute);
    customGeometry->addAttribute(textureCoordinateAttribute);

    customMeshRenderer->setInstanceCount(1);
    customMeshRenderer->setBaseVertex(0);
    customMeshRenderer->setBaseInstance(0);
    customMeshRenderer->setPrimitiveType(Qt3DRender::QGeometryRenderer::Triangles);
    customMeshRenderer->setGeometry(customGeometry);
    // 4 faces of 3 points
    customMeshRenderer->setPrimitiveCount(12);

    customMeshEntity->addComponent(customMeshRenderer);
            customMeshEntity->transform()->setScale(10.0f);

    engine.setRootEntity(rootEntity);
    window.showNormal();