DebugTools: utility to get buffer data on OpenGL ES.

src/Magnum/Buffer.h

@@ -1066,7 +1066,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
          *      @fn_gl_extension{GetNamedBufferSubData,EXT,direct_state_access},
          *      eventually @fn_gl{GetBufferSubData}
          * @requires_gl Buffer data queries are not available in OpenGL ES and
-         *      WebGL. Use @ref map() in OpenGL ES instead.
+         *      WebGL. Use @ref map() or @ref DebugTools::bufferData() in
+         *      OpenGL ES instead.
          */
         /* MinGW complains loudly if the declaration doesn't also have inline */
         template<class T = char> inline Containers::Array<T> data();
@@ -1085,7 +1086,8 @@ class MAGNUM_EXPORT Buffer: public AbstractObject {
          *      @fn_gl_extension{GetNamedBufferSubData,EXT,direct_state_access},
          *      eventually @fn_gl{BindBuffer} and @fn_gl{GetBufferSubData}
          * @requires_gl Buffer data queries are not available in OpenGL ES and
-         *      WebGL. Use @ref map() in OpenGL ES instead.
+         *      WebGL. Use @ref map() or @ref DebugTools::bufferData() in
+         *      OpenGL ES instead.
          */
         /* MinGW complains loudly if the declaration doesn't also have inline */
         template<class T = char> inline Containers::Array<T> subData(GLintptr offset, GLsizeiptr size);

src/Magnum/DebugTools/BufferData.cpp

@@ -0,0 +1,38 @@
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016
+              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 "BufferData.h"
+
+#ifndef MAGNUM_TARGET_WEBGL
+namespace Magnum { namespace DebugTools { namespace Implementation {
+
+void bufferSubData(Buffer& buffer, GLintptr offset, GLsizeiptr size, void* output) {
+    const char* data = buffer.map<const char>(offset, size, Buffer::MapFlag::Read);
+    std::copy(data, data + size, reinterpret_cast<char*>(output));
+    buffer.unmap();
+}
+
+}}}
+#endif

src/Magnum/DebugTools/BufferData.h

@@ -0,0 +1,81 @@
+#ifndef Magnum_DebugTools_BufferData_h
+#define Magnum_DebugTools_BufferData_h
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016
+              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.
+*/
+
+#ifndef MAGNUM_TARGET_WEBGL
+/** @file
+ * @brief Function @ref Magnum::DebugTools::bufferData(), @ref Magnum::DebugTools::bufferSubData()
+ */
+#endif
+
+#include <Corrade/Containers/Array.h>
+
+#include "Magnum/Buffer.h"
+#include "Magnum/DebugTools/visibility.h"
+
+#ifndef MAGNUM_TARGET_WEBGL
+namespace Magnum { namespace DebugTools {
+
+namespace Implementation {
+    MAGNUM_DEBUGTOOLS_EXPORT void bufferSubData(Buffer& buffer, GLintptr offset, GLsizeiptr size, void* output);
+}
+
+/**
+@brief Buffer subdata
+
+Emulates @ref Buffer::subData() call on platforms that don't support it (such
+as OpenGL ES) by using @ref Buffer::map().
+@requires_gles30 Extension @es_extension{EXT,map_buffer_range} in OpenGL ES
+    2.0.
+@requires_gles Buffer mapping is not available in WebGL.
+*/
+template<class T> Containers::Array<T> inline bufferSubData(Buffer& buffer, GLintptr offset, GLsizeiptr size) {
+    Containers::Array<T> data{std::size_t(size)};
+    if(size) Implementation::bufferSubData(buffer, offset, size*sizeof(T), data);
+    return data;
+}
+
+/**
+@brief Buffer data
+
+Emulates @ref Buffer::data() call on platforms that don't support it (such as
+OpenGL ES) by using @ref Buffer::map().
+@requires_gles30 Extension @es_extension{EXT,map_buffer_range} in OpenGL ES
+    2.0.
+@requires_gles Buffer mapping is not available in WebGL.
+*/
+template<class T = char> Containers::Array<T> inline bufferData(Buffer& buffer) {
+    const Int bufferSize = buffer.size();
+    CORRADE_ASSERT(bufferSize%sizeof(T) == 0, "Buffer::data(): the buffer size is" << bufferSize << "bytes, which can't be expressed as array of types with size" << sizeof(T), nullptr);
+    return bufferSubData<T>(buffer, 0, bufferSize/sizeof(T));
+}
+
+}}
+#else
+#error this header is not available in WebGL build
+#endif
+
+#endif

src/Magnum/DebugTools/CMakeLists.txt

@@ -36,6 +36,14 @@ set(MagnumDebugTools_HEADERS
 # Header files to display in project view of IDEs only
 set(MagnumDebugTools_PRIVATE_HEADERS )
 
+if(NOT MAGNUM_TARGET_WEBGL)
+    list(APPEND MagnumDebugTools_SRCS
+        BufferData.cpp)
+
+    list(APPEND MagnumDebugTools_HEADERS
+        BufferData.h)
+endif()
+
 if(WITH_SCENEGRAPH)
     list(APPEND MagnumDebugTools_SRCS
         ForceRenderer.cpp

src/Magnum/DebugTools/Test/BufferDataGLTest.cpp

@@ -0,0 +1,71 @@
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016
+              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/TestSuite/Compare/Container.h>
+
+#include "Magnum/DebugTools/BufferData.h"
+#include "Magnum/Test/AbstractOpenGLTester.h"
+
+namespace Magnum { namespace DebugTools { namespace Test {
+
+struct BufferDataGLTest: Magnum::Test::AbstractOpenGLTester {
+    explicit BufferDataGLTest();
+
+    void data();
+    void subData();
+};
+
+BufferDataGLTest::BufferDataGLTest() {
+    addTests({&BufferDataGLTest::data,
+              &BufferDataGLTest::subData});
+}
+
+namespace {
+    constexpr Int Data[] = {2, 7, 5, 13, 25};
+}
+
+void BufferDataGLTest::data() {
+    Buffer buffer;
+    buffer.setData(Data, BufferUsage::StaticDraw);
+    const Containers::Array<Int> contents = bufferData<Int>(buffer);
+    MAGNUM_VERIFY_NO_ERROR();
+    CORRADE_COMPARE_AS(contents,
+        Containers::ArrayView<const Int>{Data},
+        TestSuite::Compare::Container);
+}
+
+void BufferDataGLTest::subData() {
+    Buffer buffer;
+    buffer.setData(Data, BufferUsage::StaticDraw);
+    const Containers::Array<Int> contents = bufferSubData<Int>(buffer, 4, 3);
+    MAGNUM_VERIFY_NO_ERROR();
+    CORRADE_COMPARE_AS(contents,
+        Containers::ArrayView<const Int>{Data}.slice(1, 4),
+        TestSuite::Compare::Container);
+}
+
+}}}
+
+MAGNUM_GL_TEST_MAIN(Magnum::DebugTools::Test::BufferDataGLTest)

src/Magnum/DebugTools/Test/CMakeLists.txt

@@ -27,3 +27,7 @@ corrade_add_test(DebugToolsCapsuleRendererTest CapsuleRendererTest.cpp LIBRARIES
 corrade_add_test(DebugToolsCylinderRendererTest CylinderRendererTest.cpp LIBRARIES MagnumMathTestLib)
 corrade_add_test(DebugToolsForceRendererTest ForceRendererTest.cpp LIBRARIES MagnumMathTestLib)
 corrade_add_test(DebugToolsLineSegmentRendererTest LineSegmentRendererTest.cpp LIBRARIES MagnumMathTestLib)
+
+if(BUILD_GL_TESTS)
+    corrade_add_test(DebugToolsBufferDataGLTest BufferDataGLTest.cpp LIBRARIES MagnumDebugTools ${GL_TEST_LIBRARIES})
+endif()