MeshTools: test fullScreenTriangle().

Turns out the ES3 version doesn't work on SwiftShader due to broken
gl_VertexID.

src/Magnum/MeshTools/Test/CMakeLists.txt

@@ -59,3 +59,12 @@ if(WITH_PRIMITIVES)
 
     set_target_properties(MeshToolsSubdivideRemov___Benchmark PROPERTIES FOLDER "Magnum/MeshTools/Test")
 endif()
+
+if(BUILD_GL_TESTS)
+    corrade_add_resource(FullScreenTriangleGLTest_RESOURCES resources.conf)
+    set_target_properties(FullScreenTriangleGLTest_RESOURCES-dependencies PROPERTIES FOLDER "Magnum/MeshTools/Test")
+
+    corrade_add_test(MeshToolsFullScreenTriangleGLTest
+        FullScreenTriangleGLTest.cpp ${FullScreenTriangleGLTest_RESOURCES}
+        LIBRARIES MagnumMeshTools MagnumGL MagnumOpenGLTester)
+endif()

src/Magnum/MeshTools/Test/FullScreenTriangleGLTest.cpp

@@ -0,0 +1,144 @@
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019
+              Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include <Corrade/Containers/Array.h>
+#include <Corrade/Containers/Reference.h>
+#include <Corrade/TestSuite/Compare/Container.h>
+#include <Corrade/Utility/Resource.h>
+
+#include "Magnum/Image.h"
+#include "Magnum/PixelFormat.h"
+#include "Magnum/GL/AbstractShaderProgram.h"
+#include "Magnum/GL/Framebuffer.h"
+#include "Magnum/GL/Mesh.h"
+#include "Magnum/GL/OpenGLTester.h"
+#include "Magnum/GL/Renderbuffer.h"
+#include "Magnum/GL/RenderbufferFormat.h"
+#include "Magnum/GL/Shader.h"
+#include "Magnum/GL/Version.h"
+#include "Magnum/Math/Color.h"
+#include "Magnum/MeshTools/FullScreenTriangle.h"
+#include "Magnum/Shaders/Implementation/CreateCompatibilityShader.h"
+
+namespace Magnum { namespace MeshTools { namespace Test { namespace {
+
+struct FullScreenTriangleGLTest: GL::OpenGLTester {
+    explicit FullScreenTriangleGLTest();
+
+    void test();
+};
+
+constexpr struct {
+    const char* name;
+    GL::Version version;
+} VersionData[] {
+    #ifndef MAGNUM_TARGET_GLES
+    {"GL 2.1", GL::Version::GL210},
+    {"GL 3.0", GL::Version::GL300}
+    #else
+    {"GLES 2.0", GL::Version::GLES200},
+    #ifndef MAGNUM_TARGET_GLES2
+    {"GLES 3.0", GL::Version::GLES300}
+    #endif
+    #endif
+};
+
+FullScreenTriangleGLTest::FullScreenTriangleGLTest() {
+    addInstancedTests({&FullScreenTriangleGLTest::test},
+        Containers::arraySize(VersionData));
+}
+
+void FullScreenTriangleGLTest::test() {
+    auto&& data = VersionData[testCaseInstanceId()];
+    setTestCaseDescription(data.name);
+
+    struct FullscreenFlatShader: GL::AbstractShaderProgram {
+        FullscreenFlatShader(GL::Version version) {
+            Utility::Resource rs{"FullScreenTriangleTest"};
+
+            GL::Shader vert = Shaders::Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Vertex);
+            vert.addSource(rs.get("FullScreenTriangle.glsl"))
+                .addSource(R"(
+void main() {
+    fullScreenTriangle();
+}
+                )");
+
+            GL::Shader frag = Shaders::Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Fragment);
+            frag.addSource(R"(
+#ifdef NEW_GLSL
+out lowp vec4 fragmentColor;
+#else
+#define fragmentColor gl_FragColor
+#endif
+
+void main() {
+    fragmentColor = vec4(1.0, 0.5, 1.0, 0.5);
+}
+            )");
+
+            CORRADE_INTERNAL_ASSERT_OUTPUT(GL::Shader::compile({vert, frag}));
+
+            attachShaders({vert, frag});
+
+            CORRADE_INTERNAL_ASSERT_OUTPUT(link());
+        }
+    } shader{data.version};
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    GL::Renderbuffer color;
+    color.setStorage(
+        #ifndef MAGNUM_TARGET_GLES2
+        GL::RenderbufferFormat::RGBA8,
+        #else
+        GL::RenderbufferFormat::RGBA4,
+        #endif
+        Vector2i{4});
+    GL::Framebuffer framebuffer{{{}, Vector2i{4}}};
+    framebuffer.attachRenderbuffer(GL::Framebuffer::ColorAttachment{0}, color)
+        .bind();
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    GL::Mesh mesh = fullScreenTriangle(data.version);
+    mesh.draw(shader);
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    using namespace Math::Literals;
+
+    Image2D image = framebuffer.read({{}, Vector2i{4}}, PixelFormat::RGBA8Unorm);
+    CORRADE_COMPARE_AS(Containers::arrayCast<Color4ub>(image.data()), Containers::arrayView(Containers::Array<Color4ub>{Containers::InPlaceInit, {
+        0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba,
+        0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba,
+        0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba,
+        0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba, 0xff80ff80_rgba
+    }}), TestSuite::Compare::Container);
+}
+
+}}}}
+
+CORRADE_TEST_MAIN(Magnum::MeshTools::Test::FullScreenTriangleGLTest)

src/Magnum/MeshTools/Test/resources.conf

@@ -0,0 +1,9 @@
+group=FullScreenTriangleTest
+
+[file]
+filename=../../Shaders/FullScreenTriangle.glsl
+alias=FullScreenTriangle.glsl
+
+[file]
+filename=../../Shaders/compatibility.glsl
+alias=compatibility.glsl