Implemented CHROMIUM_map_sub for Buffer.

src/Buffer.cpp

@@ -78,6 +78,14 @@ void Buffer::initializeContextBasedFunctionality(Context* context) {
     #endif
 }
 
+Buffer::Buffer(Buffer::Target targetHint): _targetHint(targetHint)
+    #ifdef CORRADE_TARGET_NACL
+    , _mappedBuffer(nullptr)
+    #endif
+{
+    glGenBuffers(1, &_id);
+}
+
 Buffer::~Buffer() {
     GLuint* bindings = Context::current()->state()->buffer->bindings;
 
@@ -127,6 +135,31 @@ Int Buffer::size() {
     return size;
 }
 
+#ifdef MAGNUM_TARGET_GLES2
+void* Buffer::mapSub(const GLintptr offset, const GLsizeiptr length, const MapAccess access) {
+    /** @todo Enable also in Emscripten (?) when extension wrangler is available */
+    #ifdef CORRADE_TARGET_NACL
+    CORRADE_ASSERT(!_mappedBuffer, "Buffer::mapSub(): the buffer is already mapped", nullptr);
+    return _mappedBuffer = glMapBufferSubDataCHROMIUM(static_cast<GLenum>(bindInternal(_targetHint)), offset, length, GLenum(access));
+    #else
+    CORRADE_INTERNAL_ASSERT(false);
+    static_cast<void>(offset);
+    static_cast<void>(length);
+    static_cast<void>(access);
+    #endif
+}
+
+void Buffer::unmapSub() {
+    #ifdef CORRADE_TARGET_NACL
+    CORRADE_ASSERT(_mappedBuffer, "Buffer::unmapSub(): the buffer is not mapped", );
+    glUnmapBufferSubDataCHROMIUM(_mappedBuffer);
+    _mappedBuffer = nullptr;
+    #else
+    CORRADE_INTERNAL_ASSERT(false);
+    #endif
+}
+#endif
+
 #ifndef MAGNUM_TARGET_GLES2
 void Buffer::copyImplementationDefault(Buffer* read, Buffer* write, GLintptr readOffset, GLintptr writeOffset, GLsizeiptr size) {
     glCopyBufferSubData(static_cast<GLenum>(read->bindInternal(Target::CopyRead)), static_cast<GLenum>(write->bindInternal(Target::CopyWrite)), readOffset, writeOffset, size);

src/Buffer.h

@@ -324,9 +324,10 @@ class MAGNUM_EXPORT Buffer {
          *
          * @deprecated Prefer to use @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
          *      instead, as it has more complete set of features.
-         * @see map(MapAccess)
-         * @requires_es_extension %Extension @es_extension{OES,mapbuffer} in
-         *      OpenGL ES 2.0, use @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
+         * @see map(MapAccess), mapSub()
+         * @requires_es_extension %Extension @es_extension{OES,mapbuffer} or
+         *      @es_extension{CHROMIUM,map_sub} in OpenGL ES 2.0, use
+         *      @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
          *      in OpenGL ES 3.0 instead.
          */
         enum class MapAccess: GLenum {
@@ -471,9 +472,7 @@ class MAGNUM_EXPORT Buffer {
          * Generates new OpenGL buffer.
          * @see @fn_gl{GenBuffers}
          */
-        explicit Buffer(Target targetHint = Target::Array): _targetHint(targetHint) {
-            glGenBuffers(1, &_id);
-        }
+        explicit Buffer(Target targetHint = Target::Array);
 
         /**
          * @brief Destructor
@@ -728,6 +727,27 @@ class MAGNUM_EXPORT Buffer {
         }
         #endif
 
+        #if defined(MAGNUM_TARGET_GLES2) || defined(DOXYGEN_GENERATING_OUTPUT)
+        /**
+         * @brief Map portion of buffer to client memory
+         * @param offset    Offset into the buffer
+         * @param length    Length of the mapped memory
+         * @param access    Access
+         * @return Pointer to buffer data
+         *
+         * If the buffer is not already bound somewhere, it is bound to hinted
+         * target before the operation.
+         * @deprecated Prefer to use @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
+         *      instead, as it has more complete set of features.
+         * @see unmapSub(), setTargetHint(), @fn_gl_extension{MapBufferSubData,CHROMIUM,map_sub}
+         * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+         *      @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
+         *      instead.
+         * @requires_es_extension %Extension @es_extension{CHROMIUM,map_sub}
+         */
+        void* mapSub(GLintptr offset, GLsizeiptr length, MapAccess access);
+        #endif
+
         /**
          * @brief Map buffer to client memory
          * @param offset    Offset into the buffer
@@ -789,6 +809,21 @@ class MAGNUM_EXPORT Buffer {
             return (this->*unmapImplementation)();
         }
 
+        #if defined(MAGNUM_TARGET_GLES2) || defined(DOXYGEN_GENERATING_OUTPUT)
+        /**
+         * @brief Unmap portion of buffer
+         *
+         * Unmaps portion of buffer previously mapped with mapSub(),
+         * invalidating the pointer returned by the function.
+         * @see @fn_gl_extension{UnmapBufferSubData,CHROMIUM,map_sub}
+         * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+         *      @ref Magnum::Buffer::map(GLintptr, GLsizeiptr, MapFlags) "map(GLintptr, GLsizeiptr, MapFlags)"
+         *      instead.
+         * @requires_es_extension %Extension @es_extension{CHROMIUM,map_sub}
+         */
+        void unmapSub();
+        #endif
+
     private:
         static void MAGNUM_LOCAL initializeContextBasedFunctionality(Context* context);
 
@@ -878,6 +913,9 @@ class MAGNUM_EXPORT Buffer {
 
         GLuint _id;
         Target _targetHint;
+        #ifdef CORRADE_TARGET_NACL
+        void* _mappedBuffer;
+        #endif
 };
 
 CORRADE_ENUMSET_OPERATORS(Buffer::MapFlags)

src/OpenGL.h

@@ -40,6 +40,10 @@
    to NaCl's gl2ext.h we are including our own to prevent undeclared symbol
    errors with some recent extensions. */
 #elif defined(CORRADE_TARGET_NACL)
+
+/* Enable function prototypes (the supported ones shouldn't fail at link time) */
+#define GL_GLEXT_PROTOTYPES
+
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #undef __gl2ext_h_

src/Test/BufferGLTest.cpp

@@ -38,6 +38,9 @@ class BufferGLTest: public AbstractOpenGLTester {
         void construct();
         void data();
         void map();
+        #ifdef MAGNUM_TARGET_GLES2
+        void mapSub();
+        #endif
         void mapRange();
         void mapRangeExplicitFlush();
         #ifndef MAGNUM_TARGET_GLES2
@@ -52,6 +55,9 @@ BufferGLTest::BufferGLTest() {
     addTests({&BufferGLTest::construct,
               &BufferGLTest::data,
               &BufferGLTest::map,
+              #ifdef MAGNUM_TARGET_GLES2
+              &BufferGLTest::mapSub,
+              #endif
               &BufferGLTest::mapRange,
               &BufferGLTest::mapRangeExplicitFlush,
               #ifndef MAGNUM_TARGET_GLES2
@@ -147,6 +153,29 @@ void BufferGLTest::map() {
 }
 #endif
 
+#ifdef MAGNUM_TARGET_GLES2
+void BufferGLTest::mapSub() {
+    if(!Context::current()->isExtensionSupported<Extensions::GL::CHROMIUM::map_sub>())
+        CORRADE_SKIP(Extensions::GL::CHROMIUM::map_sub::string() + std::string(" is not supported"));
+
+    Buffer buffer;
+
+    constexpr char data[] = {2, 7, 5, 13, 25};
+    buffer.setData(data, Buffer::Usage::StaticDraw);
+
+    char* contents = reinterpret_cast<char*>(buffer.mapSub(1, 4, Buffer::MapAccess::WriteOnly));
+    MAGNUM_VERIFY_NO_ERROR();
+
+    CORRADE_VERIFY(contents);
+    contents[3] = 107;
+
+    buffer.unmapSub();
+    MAGNUM_VERIFY_NO_ERROR();
+
+    /** @todo How to verify the contents in ES? */
+}
+#endif
+
 void BufferGLTest::mapRange() {
     #ifndef MAGNUM_TARGET_GLES2
     if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::map_buffer_range>())