qt5base-lts/tests/manual/rhi/imguirenderer/imguirenderer.cpp

// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

#define EXAMPLEFW_IMGUI
#include "../shared/examplefw.h"

#include "../shared/cube.h"

struct {
    QMatrix4x4 winProj;
    QList<QRhiResource *> releasePool;
    QRhiResourceUpdateBatch *initialUpdates = nullptr;
    QRhiBuffer *vbuf = nullptr;
    QRhiBuffer *ubuf = nullptr;
    QRhiTexture *tex = nullptr;
    QRhiSampler *sampler = nullptr;
    QRhiShaderResourceBindings *srb = nullptr;
    QRhiGraphicsPipeline *ps = nullptr;
    bool showDemoWindow = true;
    float rotation = 0.0f;
} d;

void Window::customInit()
{
    d.initialUpdates = m_r->nextResourceUpdateBatch();

    d.vbuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(cube));
    d.vbuf->create();
    d.releasePool << d.vbuf;

    d.initialUpdates->uploadStaticBuffer(d.vbuf, cube);

    d.ubuf = m_r->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, 68);
    d.ubuf->create();
    d.releasePool << d.ubuf;
    float opacity = 1.0f;
    d.initialUpdates->updateDynamicBuffer(d.ubuf, 64, 4, &opacity);

    QImage image = QImage(QLatin1String(":/qt256.png")).convertToFormat(QImage::Format_RGBA8888).mirrored();
    d.tex = m_r->newTexture(QRhiTexture::RGBA8, QSize(image.width(), image.height()), 1, {});
    d.releasePool << d.tex;
    d.tex->create();
    d.initialUpdates->uploadTexture(d.tex, image);

    d.sampler = m_r->newSampler(QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
                                QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge);
    d.releasePool << d.sampler;
    d.sampler->create();

    d.srb = m_r->newShaderResourceBindings();
    d.releasePool << d.srb;
    d.srb->setBindings({
        QRhiShaderResourceBinding::uniformBuffer(0, QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage, d.ubuf),
        QRhiShaderResourceBinding::sampledTexture(1, QRhiShaderResourceBinding::FragmentStage, d.tex, d.sampler)
    });
    d.srb->create();

    d.ps = m_r->newGraphicsPipeline();
    d.releasePool << d.ps;
    d.ps->setCullMode(QRhiGraphicsPipeline::Back);
    const QRhiShaderStage stages[] = {
        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/texture.vert.qsb")) },
        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/texture.frag.qsb")) }
    };
    d.ps->setShaderStages(stages, stages + 2);
    QRhiVertexInputLayout inputLayout;
    inputLayout.setBindings({
        { 3 * sizeof(float) },
        { 2 * sizeof(float) }
    });
    inputLayout.setAttributes({
        { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
        { 1, 1, QRhiVertexInputAttribute::Float2, 0 }
    });
    d.ps->setVertexInputLayout(inputLayout);
    d.ps->setShaderResourceBindings(d.srb);
    d.ps->setRenderPassDescriptor(m_rp);
    d.ps->create();
}

void Window::customRelease()
{
    qDeleteAll(d.releasePool);
    d.releasePool.clear();
}

void Window::customRender()
{
    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
    QRhiResourceUpdateBatch *u = m_r->nextResourceUpdateBatch();
    if (d.initialUpdates) {
        u->merge(d.initialUpdates);
        d.initialUpdates->release();
        d.initialUpdates = nullptr;
    }

    QMatrix4x4 mvp = m_proj;
    mvp.rotate(d.rotation, 0, 1, 0);
    u->updateDynamicBuffer(d.ubuf, 0, 64, mvp.constData());

    const QSize outputSizeInPixels = m_sc->currentPixelSize();
    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);

    cb->setGraphicsPipeline(d.ps);
    cb->setViewport(QRhiViewport(0, 0, outputSizeInPixels.width(), outputSizeInPixels.height()));
    cb->setShaderResources();
    const QRhiCommandBuffer::VertexInput vbufBindings[] = {
        { d.vbuf, 0 },
        { d.vbuf, quint32(36 * 3 * sizeof(float)) }
    };
    cb->setVertexInput(0, 2, vbufBindings);
    cb->draw(36);

    m_imguiRenderer->render();

    cb->endPass();
}

void Window::customGui()
{
    ImGui::ShowDemoWindow(&d.showDemoWindow);

    ImGui::SetNextWindowPos(ImVec2(50, 120), ImGuiCond_FirstUseEver);
    ImGui::SetNextWindowSize(ImVec2(400, 100), ImGuiCond_FirstUseEver);
    ImGui::Begin("Test");
    ImGui::SliderFloat("Rotation", &d.rotation, 0.0f, 360.0f);
    ImGui::End();
}