GL/DebugTools: read buffer data on WebGL 2.0

package/ci/circleci.yml

@@ -19,7 +19,7 @@ executors:
   xcode-11_6:
     macos:
       xcode: 11.6.0
-  emscripten:
+  emscripten1:
     docker:
     # 1.39.0 is the oldest on Docker. Anything before 1.39.2 is useless as emar
     # randomly asserts: https://github.com/emscripten-core/emscripten/pull/9742
@@ -28,6 +28,12 @@ executors:
     # https://github.com/mosra/magnum/issues/413,
     # https://github.com/emscripten-core/emscripten/pull/10161
     - image: emscripten/emsdk:1.39.6-upstream
+  emscripten2:
+    docker:
+    # Used by the webgl2 job. First version that exposes glGetBufferSubData()
+    # so GLES3 tests can read buffer data without having to check the
+    # Emscripten version.
+    - image: emscripten/emsdk:2.0.17
   android-29:
     machine:
       image: android:202102-01
@@ -512,7 +518,7 @@ jobs:
     - lcov
 
   emscripten-webgl1:
-    executor: emscripten
+    executor: emscripten1
     environment:
       # STUPID yml interprets unquoted ON as a boolean
       TARGET_GLES2: "ON"
@@ -523,7 +529,7 @@ jobs:
         script: emscripten.sh
 
   emscripten-webgl2:
-    executor: emscripten
+    executor: emscripten2
     environment:
       # STUPID yml interprets unquoted OFF as a boolean
       TARGET_GLES2: "OFF"

src/Magnum/DebugTools/BufferData.h

@@ -25,7 +25,7 @@
     DEALINGS IN THE SOFTWARE.
 */
 
-#if defined(MAGNUM_TARGET_GL) && !defined(MAGNUM_TARGET_WEBGL)
+#if defined(MAGNUM_TARGET_GL) && !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
 /** @file
  * @brief Function @ref Magnum::DebugTools::bufferData(), @ref Magnum::DebugTools::bufferSubData()
  */
@@ -36,7 +36,7 @@
 #include "Magnum/GL/Buffer.h"
 #include "Magnum/DebugTools/visibility.h"
 
-#if defined(MAGNUM_TARGET_GL) && !defined(MAGNUM_TARGET_WEBGL)
+#if defined(MAGNUM_TARGET_GL) && !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
 namespace Magnum { namespace DebugTools {
 
 namespace Implementation {
@@ -47,35 +47,46 @@ namespace Implementation {
 @brief Buffer subdata
 
 Emulates @ref GL::Buffer::subData() call on platforms that don't support it
-(such as OpenGL ES) by using @ref GL::Buffer::map().
+(such as OpenGL ES) by using @ref GL::Buffer::mapRead(). On desktop GL and
+WebGL 2.0 it's just an alias to @ref GL::Buffer::subData().
 
 @note This function is available only if Magnum is compiled with
     @ref MAGNUM_TARGET_GL "TARGET_GL" enabled (done by default). See
     @ref building-features for more information.
 
 @requires_gles30 Extension @gl_extension{EXT,map_buffer_range} in OpenGL ES
     2.0.
-@requires_gles Buffer mapping is not available in WebGL.
+@requires_webgl20 Buffer data queries or buffer mapping are not available in
+    WebGL 1.0.
 */
-template<class T> Containers::Array<T> inline bufferSubData(GL::Buffer& buffer, GLintptr offset, GLsizeiptr size) {
+template<class T = char> Containers::Array<T> inline bufferSubData(GL::Buffer& buffer, GLintptr offset, GLsizeiptr size) {
+    if(!size) return {};
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_WEBGL)
+    Containers::Array<char> data = buffer.subData(offset, size*sizeof(T));
+    CORRADE_INTERNAL_ASSERT(!data.deleter());
+    return Containers::Array<T>{reinterpret_cast<T*>(data.release()), std::size_t(size)};
+    #else
     Containers::Array<T> data{std::size_t(size)};
-    if(size) Implementation::bufferSubData(buffer, offset, size*sizeof(T), data);
+    Implementation::bufferSubData(buffer, offset, size*sizeof(T), data);
     return data;
+    #endif
 }
 
 /**
 @brief Buffer data
 
 Emulates @ref GL::Buffer::data() call on platforms that don't support it (such
-as OpenGL ES) by using @ref GL::Buffer::map().
+as OpenGL ES) by using @ref GL::Buffer::mapRead(). On desktop GL and WebGL 2.0
+it's just an alias to @ref GL::Buffer::data().
 
 @note This function is available only if Magnum is compiled with
     @ref MAGNUM_TARGET_GL "TARGET_GL" enabled (done by default). See
     @ref building-features for more information.
 
 @requires_gles30 Extension @gl_extension{EXT,map_buffer_range} in OpenGL ES
     2.0.
-@requires_gles Buffer mapping is not available in WebGL.
+@requires_webgl20 Buffer data queries or buffer mapping are not available in
+    WebGL 1.0.
 */
 template<class T = char> Containers::Array<T> inline bufferData(GL::Buffer& buffer) {
     const Int bufferSize = buffer.size();
@@ -85,7 +96,7 @@ template<class T = char> Containers::Array<T> inline bufferData(GL::Buffer& buff
 
 }}
 #else
-#error this header is available only in the OpenGL (ES) build and not available in the WebGL build
+#error this header is not available in the WebGL 1.0 build
 #endif
 
 #endif

src/Magnum/DebugTools/CMakeLists.txt

@@ -72,7 +72,7 @@ if(TARGET_GL)
         endif()
     endif()
 
-    if(NOT MAGNUM_TARGET_WEBGL)
+    if(NOT (MAGNUM_TARGET_WEBGL AND MAGNUM_TARGET_GLES2))
         list(APPEND MagnumDebugTools_SRCS
             BufferData.cpp)
 

src/Magnum/DebugTools/Test/BufferDataGLTest.cpp

@@ -47,37 +47,51 @@ BufferDataGLTest::BufferDataGLTest() {
 constexpr Int Data[] = {2, 7, 5, 13, 25};
 
 void BufferDataGLTest::data() {
-    #ifndef MAGNUM_TARGET_GLES
-    if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::map_buffer_range>())
-        CORRADE_SKIP(GL::Extensions::ARB::map_buffer_range::string() << "is not supported.");
-    #elif defined(MAGNUM_TARGET_GLES2)
+    #ifdef MAGNUM_TARGET_GLES2
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::EXT::map_buffer_range>())
         CORRADE_SKIP(GL::Extensions::EXT::map_buffer_range::string() << "is not supported.");
     #endif
 
     GL::Buffer buffer;
+
+    const Containers::Array<Int> emptyContents = bufferData<Int>(buffer);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_VERIFY(emptyContents.isEmpty());
+
     buffer.setData(Data, GL::BufferUsage::StaticDraw);
-    const Containers::Array<Int> contents = bufferData<Int>(buffer);
+
+    const Containers::Array<char> contents = bufferData(buffer);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_COMPARE_AS(contents,
+        Containers::arrayCast<const char>(Containers::arrayView(Data)),
+        TestSuite::Compare::Container);
+    const Containers::Array<Int> intContents = bufferData<Int>(buffer);
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(contents, Containers::arrayView(Data),
+    CORRADE_COMPARE_AS(intContents, Containers::arrayView(Data),
         TestSuite::Compare::Container);
 }
 
 void BufferDataGLTest::subData() {
-    #ifndef MAGNUM_TARGET_GLES
-    if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::map_buffer_range>())
-        CORRADE_SKIP(GL::Extensions::ARB::map_buffer_range::string() << "is not supported.");
-    #elif defined(MAGNUM_TARGET_GLES2)
+    #ifdef MAGNUM_TARGET_GLES2
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::EXT::map_buffer_range>())
         CORRADE_SKIP(GL::Extensions::EXT::map_buffer_range::string() << "is not supported.");
     #endif
 
     GL::Buffer buffer;
     buffer.setData(Data, GL::BufferUsage::StaticDraw);
-    const Containers::Array<Int> contents = bufferSubData<Int>(buffer, 4, 3);
+
+    const Containers::Array<char> contents = bufferSubData(buffer, 4, 3*4);
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(contents, Containers::arrayView(Data).slice(1, 4),
+    CORRADE_COMPARE_AS(contents,
+        Containers::arrayCast<const char>(Containers::arrayView(Data).slice(1, 4)),
         TestSuite::Compare::Container);
+    const Containers::Array<Int> intContents = bufferSubData<Int>(buffer, 4, 3);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_COMPARE_AS(intContents, Containers::arrayView(Data).slice(1, 4),
+        TestSuite::Compare::Container);
+    const Containers::Array<Int> emptyContents = bufferSubData<Int>(buffer, 4, 0);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_VERIFY(emptyContents.isEmpty());
 }
 
 }}}}

src/Magnum/DebugTools/Test/CMakeLists.txt

@@ -118,7 +118,7 @@ if(TARGET_GL)
         corrade_add_test(DebugToolsTextureImageGLTest TextureImageGLTest.cpp
             LIBRARIES MagnumDebugTools MagnumOpenGLTester)
 
-        if(NOT MAGNUM_TARGET_WEBGL)
+        if(NOT (MAGNUM_TARGET_WEBGL AND MAGNUM_TARGET_GLES2))
             corrade_add_test(DebugToolsBufferDataGLTest BufferDataGLTest.cpp
                 LIBRARIES MagnumDebugTools MagnumOpenGLTester)
         endif()

src/Magnum/GL/Buffer.cpp

@@ -329,7 +329,7 @@ Int Buffer::size() {
     return size;
 }
 
-#ifndef MAGNUM_TARGET_GLES
+#if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
 Containers::Array<char> Buffer::data() {
     return subData(0, size());
 }
@@ -372,7 +372,7 @@ Buffer& Buffer::flushMappedRange(const GLintptr offset, const GLsizeiptr length)
 bool Buffer::unmap() { return (this->*Context::current().state().buffer.unmapImplementation)(); }
 #endif
 
-#ifndef MAGNUM_TARGET_GLES
+#if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
 Containers::Array<char> Buffer::subData(const GLintptr offset, const GLsizeiptr size) {
     Containers::Array<char> data(size);
     if(size) (this->*Context::current().state().buffer.getSubDataImplementation)(offset, size, data);
@@ -468,11 +468,13 @@ void Buffer::getParameterImplementationDSA(const GLenum value, GLint* const data
 }
 #endif
 
-#ifndef MAGNUM_TARGET_GLES
+#if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
 void Buffer::getSubDataImplementationDefault(const GLintptr offset, const GLsizeiptr size, GLvoid* const data) {
     glGetBufferSubData(GLenum(bindSomewhereInternal(_targetHint)), offset, size, data);
 }
+#endif
 
+#ifndef MAGNUM_TARGET_GLES
 void Buffer::getSubDataImplementationDSA(const GLintptr offset, const GLsizeiptr size, GLvoid* const data) {
     glGetNamedBufferSubData(_id, offset, size, data);
 }

src/Magnum/GL/Buffer.h

@@ -1089,7 +1089,7 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
          */
         Int size();
 
-        #ifndef MAGNUM_TARGET_GLES
+        #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
         /**
          * @brief Buffer data
          *
@@ -1101,9 +1101,11 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
          *      eventually @fn_gl{BindBuffer} and @fn_gl{GetBufferParameter}
          *      with @def_gl{BUFFER_SIZE}, then @fn_gl2_keyword{GetNamedBufferSubData,GetBufferSubData},
          *      eventually @fn_gl_keyword{GetBufferSubData}
-         * @requires_gl Buffer data queries are not available in OpenGL ES and
-         *      WebGL. Use @ref map(), @ref mapRead() or @ref DebugTools::bufferData()
-         *      in OpenGL ES instead.
+         * @requires_gl Buffer data queries are not available in OpenGL ES. Use
+         *      @ref map(), @ref mapRead() or @ref DebugTools::bufferData()
+         *      instead.
+         * @requires_webgl20 Buffer data queries are not available in
+         *      WebGL 1.0. Emscripten 2.0.17 or higher is required in WebGL2.
          */
         Containers::Array<char> data();
 
@@ -1119,9 +1121,11 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
          * @see @ref size(), @ref data(), @ref setSubData(), @ref setTargetHint(),
          *      @fn_gl2_keyword{GetNamedBufferSubData,GetBufferSubData},
          *      eventually @fn_gl{BindBuffer} and @fn_gl_keyword{GetBufferSubData}
-         * @requires_gl Buffer data queries are not available in OpenGL ES and
-         *      WebGL. Use @ref map(), @ref mapRead() or @ref DebugTools::bufferData()
-         *      in OpenGL ES instead.
+         * @requires_gl Buffer data queries are not available in OpenGL ES. Use
+         *      @ref map(), @ref mapRead() or @ref DebugTools::bufferData() in
+         *      OpenGL ES instead.
+         * @requires_webgl20 Buffer data queries are not available in
+         *      WebGL 1.0. Emscripten 2.0.17 or higher is required in WebGL2.
          */
         Containers::Array<char> subData(GLintptr offset, GLsizeiptr size);
         #endif
@@ -1357,8 +1361,10 @@ class MAGNUM_GL_EXPORT Buffer: public AbstractObject {
         void MAGNUM_GL_LOCAL getParameterImplementationDSA(GLenum value, GLint* data);
         #endif
 
-        #ifndef MAGNUM_TARGET_GLES
+        #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
         void MAGNUM_GL_LOCAL getSubDataImplementationDefault(GLintptr offset, GLsizeiptr size, GLvoid* data);
+        #endif
+        #ifndef MAGNUM_TARGET_GLES
         void MAGNUM_GL_LOCAL getSubDataImplementationDSA(GLintptr offset, GLsizeiptr size, GLvoid* data);
         #endif
 

src/Magnum/GL/Implementation/BufferState.cpp

@@ -126,7 +126,7 @@ BufferState::BufferState(Context& context, Containers::StaticArrayView<Implement
         storageImplementation = &Buffer::storageImplementationDefault;
         #endif
         getParameterImplementation = &Buffer::getParameterImplementationDefault;
-        #ifndef MAGNUM_TARGET_GLES
+        #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
         getSubDataImplementation = &Buffer::getSubDataImplementationDefault;
         #endif
         dataImplementation = &Buffer::dataImplementationDefault;

src/Magnum/GL/Implementation/BufferState.h

@@ -59,7 +59,7 @@ struct BufferState {
     void(Buffer::*storageImplementation)(Containers::ArrayView<const void>, Buffer::StorageFlags);
     #endif
     void(Buffer::*getParameterImplementation)(GLenum, GLint*);
-    #ifndef MAGNUM_TARGET_GLES2
+    #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_WEBGL) && !defined(MAGNUM_TARGET_GLES2) && __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017)
     void(Buffer::*getSubDataImplementation)(GLintptr, GLsizeiptr, GLvoid*);
     #endif
     void(Buffer::*dataImplementation)(GLsizeiptr, const GLvoid*, BufferUsage);