- Qt 6.5
- Qt Quick 3D
- Qt Quick 3D Examples and Tutorials
- Qt Quick 3D - Procedural Texture Example
- Qt Quick 3D | Commercial or GPLv3

# Qt Quick 3D - Procedural Texture Example

     // Copyright (C) 2020 The Qt Company Ltd.
     // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

     #include "gradienttexture.h"

     #include <QtCore/QSize>
     #include <QtGui/QGradient>

     GradientTexture::GradientTexture()
     {
         updateTexture();
     }

     int GradientTexture::height() const
     {
         return m_height;
     }

     int GradientTexture::width() const
     {
         return m_width;
     }

     QColor GradientTexture::startColor() const
     {
         return m_startColor;
     }

     QColor GradientTexture::endColor() const
     {
         return m_endColor;
     }

     void GradientTexture::setHeight(int height)
     {
         if (m_height == height)
             return;

         m_height = height;
         emit heightChanged(m_height);
         updateTexture();
     }

     void GradientTexture::setWidth(int width)
     {
         if (m_width == width)
             return;

         m_width = width;
         emit widthChanged(m_width);
         updateTexture();
     }

     void GradientTexture::setStartColor(QColor startColor)
     {
         if (m_startColor == startColor)
             return;

         m_startColor = startColor;
         emit startColorChanged(m_startColor);
         updateTexture();
     }

     void GradientTexture::setEndColor(QColor endColor)
     {
         if (m_endColor == endColor)
             return;

         m_endColor = endColor;
         emit endColorChanged(m_endColor);
         updateTexture();
     }

     void GradientTexture::updateTexture()
     {
         setSize(QSize(m_width, m_height));
         setFormat(QQuick3DTextureData::RGBA8);
         setHasTransparency(false);
         setTextureData(generateTexture());
     }

     QByteArray GradientTexture::generateTexture()
     {
         QByteArray imageData;
         // Create a horizontal gradient between startColor and endColor

         // Create a single scanline and reuse that data for each
         QByteArray gradientScanline;
         gradientScanline.resize(m_width * 4); // RGBA8

         for (int x = 0; x < m_width; ++x) {
             QColor color = linearInterpolate(m_startColor, m_endColor, x / float(m_width));
             int offset = x * 4;
             gradientScanline.data()[offset + 0] = char(color.red());
             gradientScanline.data()[offset + 1] = char(color.green());
             gradientScanline.data()[offset + 2] = char(color.blue());
             gradientScanline.data()[offset + 3] = char(255);
         }

         for (int y = 0; y < m_height; ++y)
             imageData += gradientScanline;

         return imageData;
     }

     QColor GradientTexture::linearInterpolate(const QColor &color1, const QColor &color2, float value)
     {
         QColor output;

         output.setRedF(color1.redF() + (value * (color2.redF() - color1.redF())));
         output.setGreenF(color1.greenF() + (value * (color2.greenF() - color1.greenF())));
         output.setBlueF(color1.blueF() + (value * (color2.blueF() - color1.blueF())));

         return output;
     }