GL: allow creating a Buffer and directly filling it with data.

doc/changelog.dox

@@ -69,6 +69,8 @@ See also:
     fixes crashes on Apple macOS when attempting to modify a @ref GL::Buffer
     when a @ref GL::BufferTexture is bound. See @ref opengl-workarounds for
     more information.
+-   New @ref GL::Buffer::Buffer(Containers::ArrayView<const void>, BufferUsage)
+    constructor for directly creating buffers filled with data.
 
 @subsubsection changelog-latest-new-math Math library
 

doc/snippets/MagnumGL.cpp

@@ -425,7 +425,9 @@ GL::BufferImage2D image = framebuffer.read(framebuffer.viewport(),
 GL::Buffer buffer;
 /* [Buffer-setdata] */
 Containers::ArrayView<Vector3> data;
-buffer.setData(data, GL::BufferUsage::StaticDraw);
+buffer.setData(data);
+
+GL::Buffer buffer2{data}; // or construct & fill in a single step
 /* [Buffer-setdata] */
 }
 
@@ -433,11 +435,11 @@ buffer.setData(data, GL::BufferUsage::StaticDraw);
 GL::Buffer buffer;
 /* [Buffer-setdata-stl] */
 std::vector<Vector3> data;
-buffer.setData(data, GL::BufferUsage::StaticDraw);
+buffer.setData(data);
 /* [Buffer-setdata-stl] */
 
 /* [Buffer-setdata-allocate] */
-buffer.setData({nullptr, 200*sizeof(Vector3)}, GL::BufferUsage::StaticDraw);
+buffer.setData({nullptr, 200*sizeof(Vector3)});
 /* [Buffer-setdata-allocate] */
 }
 

src/Magnum/GL/Buffer.h

@@ -145,9 +145,10 @@ data updates.
 
 @section GL-Buffer-data-updating Data updating
 
-Default way to set or update buffer data with @ref setData() or @ref setSubData()
+Default way to set or update buffer data with @ref setData(), @ref setSubData()
-is to use @ref Corrade::Containers::ArrayView. See its documentation for
+or the shorthand @ref Buffer() constructor is to use
-more information about automatic conversions etc.
+@ref Corrade::Containers::ArrayView. See its documentation for more information
+about automatic conversions etc.
 
 @snippet MagnumGL.cpp Buffer-setdata
 
@@ -784,6 +785,42 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
          */
         explicit Buffer(NoCreateT) noexcept;
 
+        /**
+         * @brief Construct and directly fill with data
+         * @param targetHint    Target hint, see @ref setTargetHint() for more
+         *      information
+         * @param data          Data
+         * @param usage         Buffer usage
+         * @m_since_latest
+         *
+         * Equivalent to constructing via @ref Buffer(TargetHint) and then
+         * calling @ref setData().
+         */
+        explicit Buffer(TargetHint targetHint, Containers::ArrayView<const void> data, BufferUsage usage = BufferUsage::StaticDraw): Buffer{targetHint} {
+            setData(data, usage);
+        }
+
+        /**
+         * @overload
+         * @m_since_latest
+         */
+        template<class T> explicit Buffer(TargetHint targetHint, std::initializer_list<T> data, BufferUsage usage = BufferUsage::StaticDraw): Buffer{targetHint, Containers::arrayView(data), usage} {}
+
+        /**
+         * @overload
+         * @m_since_latest
+         *
+         * Equivalent to calling @ref Buffer(TargetHint, Containers::ArrayView<const void>, BufferUsage)
+         * with @ref TargetHint::Array. Unlike with
+         * @ref Buffer(TargetHint, std::initializer_list<T>, BufferUsage) an
+         * @ref std::initializer_list overload isn't provided in this case as
+         * it would cause a lot of undesired implicit conversions when using
+         * the `{}`-style construction. Use the above overload or the
+         * @ref Corrade::Containers::arrayView(std::initializer_list<T>) helper
+         * instead.
+         */
+        explicit Buffer(Containers::ArrayView<const void> data, BufferUsage usage = BufferUsage::StaticDraw): Buffer{TargetHint::Array, data, usage} {}
+
         /** @brief Copying is not allowed */
         Buffer(const Buffer&) = delete;
 

src/Magnum/GL/Test/BufferGLTest.cpp

@@ -41,6 +41,7 @@ struct BufferGLTest: OpenGLTester {
     explicit BufferGLTest();
 
     void construct();
+    void constructFromData();
     void constructMove();
     void wrap();
 
@@ -67,6 +68,7 @@ struct BufferGLTest: OpenGLTester {
 
 BufferGLTest::BufferGLTest() {
     addTests({&BufferGLTest::construct,
+              &BufferGLTest::constructFromData,
               &BufferGLTest::constructMove,
               &BufferGLTest::wrap,
 
@@ -104,6 +106,36 @@ void BufferGLTest::construct() {
     MAGNUM_VERIFY_NO_GL_ERROR();
 }
 
+void BufferGLTest::constructFromData() {
+    constexpr Int data[] = {2, 7, 5, 13, 25};
+
+    Buffer a{Buffer::TargetHint::ElementArray, data};
+    Buffer b{Buffer::TargetHint::ElementArray, {2, 7, 5, 13, 25}};
+    Buffer c{data};
+    Buffer d{{nullptr, 5*4}}; /* This should work too for reserving memory */
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    CORRADE_COMPARE(a.size(), 5*4);
+    CORRADE_COMPARE(b.size(), 5*4);
+    CORRADE_COMPARE(c.size(), 5*4);
+    CORRADE_COMPARE(d.size(), 5*4);
+
+    /** @todo How to verify the contents in ES? */
+    #ifndef MAGNUM_TARGET_GLES
+    CORRADE_COMPARE_AS(Containers::arrayCast<Int>(a.data()),
+        Containers::arrayView(data),
+        TestSuite::Compare::Container);
+    CORRADE_COMPARE_AS(Containers::arrayCast<Int>(b.data()),
+        Containers::arrayView(data),
+        TestSuite::Compare::Container);
+    CORRADE_COMPARE_AS(Containers::arrayCast<Int>(c.data()),
+        Containers::arrayView(data),
+        TestSuite::Compare::Container);
+    /* d's data is undefined, not testing */
+    #endif
+}
+
 void BufferGLTest::constructMove() {
     Buffer a;
     const Int id = a.id();