rhi: Add a manual test for simple stencil-based outline

Interesting on its own just because it exercises stencil testing,
unlike any of the other existing manual tests.

In addition it serves as a base example for how outlines could be
done, it is one possible approach at least. (render with stencil
write, then render again slightly scaled up with a solid color with
testing against the stencil buffer content)

Change-Id: I0c845a9004136f229cab037f6f0aab2f772bdd76
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

tests/manual/rhi/CMakeLists.txt

@@ -29,6 +29,7 @@ add_subdirectory(texturearray)
 add_subdirectory(polygonmode)
 add_subdirectory(tessellation)
 add_subdirectory(geometryshader)
+add_subdirectory(stenciloutline)
 if(QT_FEATURE_widgets)
     add_subdirectory(rhiwidget)
 endif()

tests/manual/rhi/shared/examplefw.h

@@ -259,7 +259,6 @@ void Window::init()
     // now onto the backend-independent init
 
     m_sc = m_r->newSwapChain();
-    // allow depth-stencil, although we do not actually enable depth test/write for the triangle
     m_ds = m_r->newRenderBuffer(QRhiRenderBuffer::DepthStencil,
                                 QSize(), // no need to set the size here, due to UsedWithSwapChainOnly
                                 sampleCount,

tests/manual/rhi/stenciloutline/CMakeLists.txt

@@ -0,0 +1,19 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_internal_add_manual_test(stenciloutline
+    GUI
+    SOURCES
+        stenciloutline.cpp
+    LIBRARIES
+        Qt::Gui
+        Qt::GuiPrivate
+)
+
+qt_internal_add_resource(stenciloutline "stenciloutline"
+    PREFIX
+        "/"
+    FILES
+        "material.frag.qsb"
+        "material.vert.qsb"
+)

tests/manual/rhi/stenciloutline/buildshaders.bat

@@ -0,0 +1,2 @@
+qsb --glsl "100 es,120,150" --hlsl 50 --msl 12 material.vert -o material.vert.qsb
+qsb --glsl "100 es,120,150" --hlsl 50 --msl 12 material.frag -o material.frag.qsb

tests/manual/rhi/stenciloutline/material.frag

@@ -0,0 +1,13 @@
+#version 440
+
+layout(location = 0) out vec4 fragColor;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+    vec3 color;
+};
+
+void main()
+{
+    fragColor = vec4(color, 1.0);
+}

tests/manual/rhi/stenciloutline/material.vert

@@ -0,0 +1,13 @@
+#version 440
+
+layout(location = 0) in vec4 position;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+    vec3 color;
+};
+
+void main()
+{
+    gl_Position = mvp  * position;
+}

tests/manual/rhi/stenciloutline/stenciloutline.cpp

@@ -0,0 +1,154 @@
+// Copyright (C) 2019 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "../shared/examplefw.h"
+#include "../shared/cube.h"
+
+static const quint32 UBUF_SIZE = 76;
+static const float OUTLINE_SIZE = 1.05f;
+
+struct {
+    QList<QRhiResource *> releasePool;
+
+    QRhiBuffer *vbuf;
+    QRhiBuffer *ubuf;
+    QRhiShaderResourceBindings *srb;
+    QRhiGraphicsPipeline *psPass1;
+    QRhiGraphicsPipeline *psPass2;
+    float rot = 0.0f;
+
+    QRhiResourceUpdateBatch *initialUpdates = nullptr;
+} 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, 2 * m_r->ubufAligned(UBUF_SIZE));
+    d.ubuf->create();
+    d.releasePool << d.ubuf;
+
+    d.srb = m_r->newShaderResourceBindings();
+    d.releasePool << d.srb;
+    d.srb->setBindings({
+            QRhiShaderResourceBinding::uniformBufferWithDynamicOffset(0, QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage, d.ubuf, UBUF_SIZE)
+        });
+    d.srb->create();
+
+    QRhiVertexInputLayout inputLayout;
+    inputLayout.setBindings({
+        { 3 * sizeof(float) },
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
+    });
+
+    const QRhiShaderStage stages[] = {
+        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/material.vert.qsb")) },
+        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/material.frag.qsb")) }
+    };
+
+    d.psPass1 = m_r->newGraphicsPipeline();
+    d.releasePool << d.psPass1;
+    d.psPass1->setShaderStages(stages, stages + 2);
+    d.psPass1->setFlags(QRhiGraphicsPipeline::UsesStencilRef);
+    d.psPass1->setDepthTest(true);
+    d.psPass1->setDepthWrite(true);
+    QRhiGraphicsPipeline::StencilOpState stencilPass1 = { QRhiGraphicsPipeline::Keep,
+                                                          QRhiGraphicsPipeline::Keep,
+                                                          QRhiGraphicsPipeline::Replace,
+                                                          QRhiGraphicsPipeline::Always };
+    d.psPass1->setStencilFront(stencilPass1);
+    d.psPass1->setCullMode(QRhiGraphicsPipeline::Back);
+    //d.psPass1->setStencilBack(stencilPass1);
+    d.psPass1->setStencilTest(true);
+    d.psPass1->setVertexInputLayout(inputLayout);
+    d.psPass1->setShaderResourceBindings(d.srb);
+    d.psPass1->setRenderPassDescriptor(m_rp);
+    d.psPass1->create();
+
+    d.psPass2 = m_r->newGraphicsPipeline();
+    d.releasePool << d.psPass2;
+    d.psPass2->setShaderStages(stages, stages + 2);
+    d.psPass2->setFlags(QRhiGraphicsPipeline::UsesStencilRef);
+    d.psPass2->setDepthTest(false);
+    d.psPass2->setDepthWrite(false);
+    QRhiGraphicsPipeline::StencilOpState stencilPass2 = { QRhiGraphicsPipeline::Keep,
+                                                          QRhiGraphicsPipeline::Keep,
+                                                          QRhiGraphicsPipeline::Replace,
+                                                          QRhiGraphicsPipeline::NotEqual };
+    d.psPass2->setStencilFront(stencilPass2);
+    d.psPass2->setCullMode(QRhiGraphicsPipeline::Back);
+    //d.psPass2->setStencilBack(stencilPass2);
+    d.psPass2->setStencilTest(true);
+    d.psPass2->setStencilWriteMask(0);
+    d.psPass2->setVertexInputLayout(inputLayout);
+    d.psPass2->setShaderResourceBindings(d.srb);
+    d.psPass2->setRenderPassDescriptor(m_rp);
+    d.psPass2->create();
+}
+
+void Window::customRelease()
+{
+    qDeleteAll(d.releasePool);
+    d.releasePool.clear();
+}
+
+void Window::customRender()
+{
+    const QSize outputSizeInPixels = m_sc->currentPixelSize();
+    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
+    QRhiResourceUpdateBatch *u = nullptr;
+    if (d.initialUpdates) {
+        u = d.initialUpdates;
+        d.initialUpdates = nullptr;
+    }
+
+    char *p = d.ubuf->beginFullDynamicBufferUpdateForCurrentFrame();
+    QMatrix4x4 mvp = m_proj;
+    mvp.rotate(d.rot, 1, 1, 0);
+    mvp.scale(0.5f);
+
+    memcpy(p, mvp.constData(), 64);
+    const float color[] = { 1.0f, 0.0f, 0.0f };
+    memcpy(p + 64, color, 3 * sizeof(float));
+
+    static const size_t pass2Ofs = m_r->ubufAligned(UBUF_SIZE);
+    mvp.scale(OUTLINE_SIZE);
+    memcpy(p + pass2Ofs, mvp.constData(), 64);
+    const float pass2Color[] = { 0.0f, 0.0f, 1.0f };
+    memcpy(p + pass2Ofs + 64, pass2Color, 3 * sizeof(float));
+
+    d.ubuf->endFullDynamicBufferUpdateForCurrentFrame();
+
+    const QRhiCommandBuffer::VertexInput vbufBinding[] = {
+        { d.vbuf, 0 },
+    };
+
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u, QRhiCommandBuffer::DoNotTrackResourcesForCompute);
+
+    cb->setGraphicsPipeline(d.psPass1);
+    cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
+    QRhiCommandBuffer::DynamicOffset pass1DynOffset = { 0, 0 };
+    cb->setShaderResources(d.srb, 1, &pass1DynOffset);
+    cb->setVertexInput(0, 1, vbufBinding);
+    cb->setStencilRef(1);
+    cb->draw(36);
+
+    cb->setGraphicsPipeline(d.psPass2);
+    QRhiCommandBuffer::DynamicOffset pass2DynOffset = { 0, m_r->ubufAligned(UBUF_SIZE) };
+    cb->setShaderResources(d.srb, 1, &pass2DynOffset);
+    cb->setVertexInput(0, 1, vbufBinding);
+    cb->setStencilRef(1);
+    cb->draw(36);
+
+    cb->endPass();
+
+    d.rot += 1;
+}