GL: make use of unmasked renderer string in Context::detectedDriver().

doc/changelog.dox

@@ -88,7 +88,8 @@ See also:
 -   Implemented @webgl_extension{WEBGL,debug_renderer_info} as
     @ref GL::Context::rendererStringUnmasked() and
     @relativeref{GL::Context,vendorStringUnmasked()} together with printing
-    those in the engine startup log if the extension is available. It also
+    those in the engine startup log if the extension is available and expanding
+    the capabilities of @ref GL::Context::detectedDriver() on WebGL. It also
     resulted in a new @cpp "firefox-deprecated-debug-renderer-info" @ce
     workaround being added, see @ref opengl-workarounds for more info.
 -   Recognizing @webgl_extension{EXT,float_blend} and

src/Magnum/GL/Context.cpp

@@ -1317,13 +1317,10 @@ Debug& operator<<(Debug& debug, const Context::DetectedDriver value) {
     switch(value) {
         /* LCOV_EXCL_START */
         #define _c(value) case Context::DetectedDriver::value: return debug << "::" #value;
-        #ifndef MAGNUM_TARGET_WEBGL
         _c(Amd)
-        #endif
         #ifdef MAGNUM_TARGET_GLES
         _c(Angle)
         #endif
-        #ifndef MAGNUM_TARGET_WEBGL
         _c(IntelWindows)
         _c(Mesa)
         _c(NVidia)
@@ -1331,7 +1328,6 @@ Debug& operator<<(Debug& debug, const Context::DetectedDriver value) {
         #ifdef MAGNUM_TARGET_GLES
         _c(SwiftShader)
         #endif
-        #endif
         #ifdef CORRADE_TARGET_ANDROID
         _c(ArmMali)
         #endif

src/Magnum/GL/Context.h

@@ -409,54 +409,45 @@ class MAGNUM_GL_EXPORT Context {
         /**
          * @brief Detected driver
          *
-         * @see @ref DetectedDriver, @ref detectedDriver()
+         * On WebGL, if @webgl_extension{WEBGL,debug_renderer_info} is not
+         * available and the browser doesn't report the real values through
+         * @ref vendorString() and @ref rendererString(), driver detection can
+         * be performed only for limited cases --- see documentation of
+         * particular values for more information.
+         * @see @ref DetectedDrivers, @ref detectedDriver()
          */
         enum class DetectedDriver: UnsignedShort {
-            #ifndef MAGNUM_TARGET_WEBGL
             /**
              * Proprietary AMD desktop drivers on Windows and Linux. In
              * contrast, AMDGPU Mesa drivers report as
              * @ref DetectedDriver::Mesa instead.
-             * @requires_gles Not detectable on WebGL, as browsers
-             *      intentionally hide most of the driver information.
              */
             Amd = 1 << 0,
-            #endif
 
             #if defined(MAGNUM_TARGET_GLES) || defined(DOXYGEN_GENERATING_OUTPUT)
             /**
              * OpenGL ES implementation by ANGLE (translated to D3D), used by
-             * browsers on Windows for WebGL. As the WebGL specification
+             * browsers on Windows for WebGL. See also
-             * explicitly disallows exposing driver information to the
+             * @ref DetectedDriver::SwiftShader. On WebGL, if
-             * application, this check cannot be done reliably. See also
+             * @webgl_extension{WEBGL,debug_renderer_info} is not available,
-             * @ref DetectedDriver::SwiftShader.
+             * the detection is done by checking if the line size range is just
+             * 1, which is always the case on D3D but not always on GL.
              * @requires_gles ANGLE doesn't support desktop OpenGL contexts.
              */
             Angle = 1 << 1,
             #endif
 
-            #ifndef MAGNUM_TARGET_WEBGL
+            /** Intel desktop drivers on Windows */
-            /**
-             * Intel desktop drivers on Windows
-             * @requires_gles Not detectable on WebGL, as browsers
-             *      intentionally hide most of the driver information.
-             */
             IntelWindows = 1 << 2,
 
             /**
              * Mesa drivers on Windows and Linux. In particular, Intel, AMD
              * and NVidia Mesa drivers match as this. See also
              * @ref DetectedDriver::Svga3D.
-             * @requires_gles Not detectable on WebGL, as browsers
-             *      intentionally hide most of the driver information.
              */
             Mesa = 1 << 3,
 
-            /**
+            /** Proprietary NVidia drivers on Windows and Linux */
-             * Proprietary NVidia drivers on Windows and Linux
-             * @requires_gles Not detectable on WebGL, as browsers
-             *      intentionally hide most of the driver information.
-             */
             NVidia = 1 << 4,
 
             /**
@@ -464,8 +455,6 @@ class MAGNUM_GL_EXPORT Context {
              * Windows and Linux guests. See https://www.mesa3d.org/vmware-guest.html
              * for more information. Detected in combination with
              * @ref DetectedDriver::Mesa.
-             * @requires_gles Not detectable on WebGL, as browsers
-             *      intentionally hide most of the driver information.
              */
             Svga3D = 1 << 5,
 
@@ -475,13 +464,11 @@ class MAGNUM_GL_EXPORT Context {
              * renderer for OpenGL ES. Usually used by browsers in cases where
              * a GPU isn't available. See also @ref DetectedDriver::Angle.
              * @requires_gles SwiftShader doesn't support desktop OpenGL
-             *      contexts. Not detectable on WebGL, as browsers
+             *      contexts.
-             *      intentionally hide most of the driver information.
              * @m_since{2019,10}
              */
             SwiftShader = 1 << 6,
             #endif
-            #endif
 
             #if defined(CORRADE_TARGET_ANDROID) || defined(DOXYGEN_GENERATING_OUTPUT)
             /**

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -429,68 +429,90 @@ auto Context::detectedDriver() -> DetectedDrivers {
 
     _detectedDrivers = DetectedDrivers{};
 
-    #if !defined(MAGNUM_TARGET_WEBGL) && !defined(CORRADE_TARGET_APPLE)
+    #ifndef CORRADE_TARGET_APPLE
-    const Containers::StringView renderer = rendererString();
+    const Containers::StringView renderer =
+        #ifndef MAGNUM_TARGET_WEBGL
+        rendererString()
+        #else
+        rendererStringUnmasked()
+        #endif
+        ;
     #endif
     #if !defined(CORRADE_TARGET_APPLE) && !defined(MAGNUM_TARGET_WEBGL)
     const Containers::StringView version = versionString();
     #endif
-    #if (!defined(CORRADE_TARGET_APPLE) && !defined(MAGNUM_TARGET_WEBGL)) || defined(MAGNUM_TARGET_GLES)
+    #if !defined(CORRADE_TARGET_APPLE) || defined(MAGNUM_TARGET_GLES)
-    const Containers::StringView vendor = vendorString();
+    const Containers::StringView vendor =
+        #ifndef MAGNUM_TARGET_WEBGL
+        vendorString()
+        #else
+        vendorStringUnmasked()
+        #endif
+        ;
     #endif
 
+    /* In some cases we can have a combination of drivers (e.g. ANGLE running
+       on top of Mesa, Mesa Zink running on top of NVidia drivers...) so the
+       detection has no early returns. */
+
     /* Apple has its own drivers */
-    #if !defined(CORRADE_TARGET_APPLE) && !defined(MAGNUM_TARGET_WEBGL)
+    /** @todo when Zink on Apple is a thing, this needs an update */
+    #ifndef CORRADE_TARGET_APPLE
     /* AMD binary desktop drivers */
     if(vendor.contains("ATI Technologies Inc."_s))
-        return *_detectedDrivers |= DetectedDriver::Amd;
+        *_detectedDrivers |= DetectedDriver::Amd;
 
     #ifdef CORRADE_TARGET_WINDOWS
     /* Intel Windows drivers */
     if(vendor.contains("Intel"_s))
-        return *_detectedDrivers |= DetectedDriver::IntelWindows;
+        *_detectedDrivers |= DetectedDriver::IntelWindows;
     #endif
 
     /* Mesa drivers */
-    if(version.contains("Mesa"_s)) {
+    #ifndef MAGNUM_TARGET_WEBGL
+    if(version.contains("Mesa"_s))
+    #else
+    if(renderer.contains("Mesa"_s))
+    #endif
+    {
         *_detectedDrivers |= DetectedDriver::Mesa;
 
         if(renderer.contains("SVGA3D"_s))
             *_detectedDrivers |= DetectedDriver::Svga3D;
 
-        return *_detectedDrivers;
+        *_detectedDrivers;
     }
 
     if(vendor.contains("NVIDIA Corporation"_s))
-        return *_detectedDrivers |= DetectedDriver::NVidia;
+        *_detectedDrivers |= DetectedDriver::NVidia;
     #endif
 
-    /** @todo there is also D3D9/D3D11 distinction on webglreport.com, is it useful? */
     #ifdef MAGNUM_TARGET_GLES
-    /* ANGLE. Can detect easily on ES, have to resort to hacks on WebGL.
+    /* ANGLE. On WebGL only if we are so lucky and have access to the unmasked
-       Sources: http://stackoverflow.com/a/20149090 + http://webglreport.com */
+       renderer string. */
-    #ifndef MAGNUM_TARGET_WEBGL
     if(renderer.contains("ANGLE"_s))
-        return *_detectedDrivers |= DetectedDriver::Angle;
+        *_detectedDrivers |= DetectedDriver::Angle;
-    #else
+    #ifdef MAGNUM_TARGET_WEBGL
-    {
+    /* Otherwise try to detect a D3D ANGLE backend by querying line width. It's
+       always exactly just 1 on D3D, usually more on GL, not sure about Metal.
+       so this is not a 100% match. Sources: http://stackoverflow.com/a/20149090
+       and http://webglreport.com */
+    else {
         Range1Di range;
         glGetIntegerv(GL_ALIASED_LINE_WIDTH_RANGE, range.data());
         if(range.min() == 1 && range.max() == 1 && vendor != "Internet Explorer"_s)
-            return *_detectedDrivers |= DetectedDriver::Angle;
+            *_detectedDrivers |= DetectedDriver::Angle;
     }
     #endif
 
-    #ifndef MAGNUM_TARGET_WEBGL
     /* SwiftShader */
     if(renderer.contains("SwiftShader"_s))
-        return *_detectedDrivers |= DetectedDriver::SwiftShader;
+        *_detectedDrivers |= DetectedDriver::SwiftShader;
-    #endif
     #endif
 
     #ifdef CORRADE_TARGET_ANDROID
     if(vendor.contains("ARM"_s) && renderer.contains("Mali"_s))
-        return *_detectedDrivers |= DetectedDriver::ArmMali;
+        *_detectedDrivers |= DetectedDriver::ArmMali;
     #endif
 
     return *_detectedDrivers;