Function processWorkItem

examples/island/Island.cpp:264–329

/////////////////////////////////////////////////////// Process a terrain generation work item. Use the vector of vertices as scratch memory and upload the data to the vertex buffer when done. ///////////////////////////////////////////////////////

///
////////////////////////////////////////////////////////////
void processWorkItem(std::vector<sf::Vertex>& vertices, const WorkItem& workItem)
{
    const unsigned int rowStart = rowBlockSize * workItem.index;

    if (rowStart >= resolution.y)
        return;

    const unsigned int rowEnd   = std::min(rowStart + rowBlockSize, resolution.y);
    const unsigned int rowCount = rowEnd - rowStart;

    for (unsigned int y = rowStart; y < rowEnd; ++y)
    {
        for (unsigned int x = 0; x < resolution.x; ++x)
        {
            const unsigned int arrayIndexBase = ((y - rowStart) * resolution.x + x) * 6;

            // Top left corner (first triangle)
            if (x > 0)
            {
                vertices[arrayIndexBase + 0] = vertices[arrayIndexBase - 6 + 5];
            }
            else if (y > rowStart)
            {
                vertices[arrayIndexBase + 0] = vertices[arrayIndexBase - resolution.x * 6 + 1];
            }
            else
            {
                vertices[arrayIndexBase + 0] = computeVertex({x, y});
            }

            // Bottom left corner (first triangle)
            if (x > 0)
            {
                vertices[arrayIndexBase + 1] = vertices[arrayIndexBase - 6 + 2];
            }
            else
            {
                vertices[arrayIndexBase + 1] = computeVertex({x, y + 1});
            }

            // Bottom right corner (first triangle)
            vertices[arrayIndexBase + 2] = computeVertex({x + 1, y + 1});

            // Top left corner (second triangle)
            vertices[arrayIndexBase + 3] = vertices[arrayIndexBase + 0];

            // Bottom right corner (second triangle)
            vertices[arrayIndexBase + 4] = vertices[arrayIndexBase + 2];

            // Top right corner (second triangle)
            if (y > rowStart)
            {
                vertices[arrayIndexBase + 5] = vertices[arrayIndexBase - resolution.x * 6 + 2];
            }
            else
            {
                vertices[arrayIndexBase + 5] = computeVertex({x + 1, y});
            }