LibWeb/WebGL: Implement WEBGL_compressed_texture_s3tc extension

Author: https://github.com/Lubrsi
Commit: https://github.com/LadybirdBrowser/ladybird/commit/958938655d5
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3385

Libraries/LibWeb/CMakeLists.txt

@@ -834,6 +834,7 @@ set(SOURCES
     WebDriver/UserPrompt.cpp
     WebGL/Extensions/ANGLEInstancedArrays.cpp
     WebGL/Extensions/OESVertexArrayObject.cpp
+    WebGL/Extensions/WebGLCompressedTextureS3tc.cpp
     WebGL/Extensions/WebGLDrawBuffers.cpp
     WebGL/Extensions/WebGLVertexArrayObjectOES.cpp
     WebGL/EventNames.cpp

Libraries/LibWeb/Forward.h

@@ -883,6 +883,7 @@ class WebGLVertexArrayObject;
 namespace Web::WebGL::Extensions {
 class ANGLEInstancedArrays;
 class OESVertexArrayObject;
+class WebGLCompressedTextureS3tc;
 class WebGLDrawBuffers;
 class WebGLVertexArrayObjectOES;
 }

Libraries/LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2025, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/WebGLCompressedTextureS3tcPrototype.h>
+#include <LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.h>
+#include <LibWeb/WebGL/OpenGLContext.h>
+
+namespace Web::WebGL::Extensions {
+
+GC_DEFINE_ALLOCATOR(WebGLCompressedTextureS3tc);
+
+JS::ThrowCompletionOr<GC::Ptr<WebGLCompressedTextureS3tc>> WebGLCompressedTextureS3tc::create(JS::Realm& realm, WebGLRenderingContextBase* context)
+{
+    return realm.create<WebGLCompressedTextureS3tc>(realm, context);
+}
+
+WebGLCompressedTextureS3tc::WebGLCompressedTextureS3tc(JS::Realm& realm, WebGLRenderingContextBase* context)
+    : PlatformObject(realm)
+    , m_context(context)
+{
+    m_context->context().request_extension("GL_EXT_texture_compression_dxt1");
+    m_context->context().request_extension("GL_ANGLE_texture_compression_dxt3");
+    m_context->context().request_extension("GL_ANGLE_texture_compression_dxt5");
+}
+
+void WebGLCompressedTextureS3tc::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(WebGLCompressedTextureS3tc);
+}
+
+void WebGLCompressedTextureS3tc::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_context->gc_cell());
+}
+
+}

Libraries/LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2025, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/WebGL/WebGLRenderingContextBase.h>
+
+namespace Web::WebGL::Extensions {
+
+class WebGLCompressedTextureS3tc : public Bindings::PlatformObject {
+    WEB_PLATFORM_OBJECT(WebGLCompressedTextureS3tc, Bindings::PlatformObject);
+    GC_DECLARE_ALLOCATOR(WebGLCompressedTextureS3tc);
+
+public:
+    static JS::ThrowCompletionOr<GC::Ptr<WebGLCompressedTextureS3tc>> create(JS::Realm&, WebGLRenderingContextBase*);
+
+protected:
+    void initialize(JS::Realm&) override;
+    void visit_edges(Visitor&) override;
+
+private:
+    WebGLCompressedTextureS3tc(JS::Realm&, WebGLRenderingContextBase*);
+
+    // FIXME: It should be GC::Ptr instead of raw pointer, but we need to make WebGLRenderingContextBase inherit from PlatformObject first.
+    WebGLRenderingContextBase* m_context;
+};
+
+}

Libraries/LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.idl

@@ -0,0 +1,16 @@
+#import <WebGL/Types.idl>
+
+// https://registry.khronos.org/webgl/extensions/WEBGL_compressed_texture_s3tc/
+// NOTE: Original WEBGL_compressed_texture_s3tc name is changed to title case,
+//       so it matches corresponding C++ class name, and does not require
+//       IDL generator to handle snake_case to TitleCase conversion.
+//       Having a different name is totally fine, because LegacyNoInterfaceObject
+//       prevents the name from being exposed to JavaScript.
+[Exposed=(Window,Worker), LegacyNoInterfaceObject]
+interface WebGLCompressedTextureS3tc {
+    // Compressed Texture Formats
+    const GLenum COMPRESSED_RGB_S3TC_DXT1_EXT = 0x83F0;
+    const GLenum COMPRESSED_RGBA_S3TC_DXT1_EXT = 0x83F1;
+    const GLenum COMPRESSED_RGBA_S3TC_DXT3_EXT = 0x83F2;
+    const GLenum COMPRESSED_RGBA_S3TC_DXT5_EXT = 0x83F3;
+};

Libraries/LibWeb/WebGL/WebGL2RenderingContext.cpp

@@ -12,8 +12,10 @@
 #include <LibWeb/Bindings/WebGL2RenderingContextPrototype.h>
 #include <LibWeb/HTML/HTMLCanvasElement.h>
 #include <LibWeb/HTML/TraversableNavigable.h>
+#include <LibWeb/Infra/Strings.h>
 #include <LibWeb/Painting/Paintable.h>
 #include <LibWeb/WebGL/EventNames.h>
+#include <LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.h>
 #include <LibWeb/WebGL/OpenGLContext.h>
 #include <LibWeb/WebGL/WebGL2RenderingContext.h>
 #include <LibWeb/WebGL/WebGLContextEvent.h>
@@ -71,6 +73,7 @@ void WebGL2RenderingContext::visit_edges(Cell::Visitor& visitor)
     Base::visit_edges(visitor);
     WebGL2RenderingContextImpl::visit_edges(visitor);
     visitor.visit(m_canvas_element);
+    visitor.visit(m_webgl_compressed_texture_s3tc_extension);
 }
 
 void WebGL2RenderingContext::present()
@@ -154,8 +157,29 @@ Optional<Vector<String>> WebGL2RenderingContext::get_supported_extensions()
     return context().get_supported_extensions();
 }
 
-JS::Object* WebGL2RenderingContext::get_extension(String const&)
+JS::Object* WebGL2RenderingContext::get_extension(String const& name)
 {
+    // Returns an object if, and only if, name is an ASCII case-insensitive match [HTML] for one of the names returned
+    // from getSupportedExtensions; otherwise, returns null. The object returned from getExtension contains any constants
+    // or functions provided by the extension. A returned object may have no constants or functions if the extension does
+    // not define any, but a unique object must still be returned. That object is used to indicate that the extension has
+    // been enabled.
+    auto supported_extensions = get_supported_extensions();
+    auto supported_extension_iterator = supported_extensions->find_if([&name](String const& supported_extension) {
+        return Infra::is_ascii_case_insensitive_match(supported_extension, name);
+    });
+    if (supported_extension_iterator == supported_extensions->end())
+        return nullptr;
+
+    if (Infra::is_ascii_case_insensitive_match(name, "WEBGL_compressed_texture_s3tc"sv)) {
+        if (!m_webgl_compressed_texture_s3tc_extension) {
+            m_webgl_compressed_texture_s3tc_extension = MUST(Extensions::WebGLCompressedTextureS3tc::create(realm(), this));
+        }
+
+        VERIFY(m_webgl_compressed_texture_s3tc_extension);
+        return m_webgl_compressed_texture_s3tc_extension;
+    }
+
     return nullptr;
 }
 

Libraries/LibWeb/WebGL/WebGL2RenderingContext.h

@@ -80,6 +80,10 @@ private:
 
     GLenum m_error { 0 };
 
+    // Extensions
+    // "Multiple calls to getExtension with the same extension string, taking into account case-insensitive comparison, must return the same object as long as the extension is enabled."
+    GC::Ptr<Extensions::WebGLCompressedTextureS3tc> m_webgl_compressed_texture_s3tc_extension;
+
     virtual void set_error(GLenum error) override;
 };
 

Libraries/LibWeb/WebGL/WebGLRenderingContext.cpp

@@ -16,6 +16,7 @@
 #include <LibWeb/WebGL/EventNames.h>
 #include <LibWeb/WebGL/Extensions/ANGLEInstancedArrays.h>
 #include <LibWeb/WebGL/Extensions/OESVertexArrayObject.h>
+#include <LibWeb/WebGL/Extensions/WebGLCompressedTextureS3tc.h>
 #include <LibWeb/WebGL/Extensions/WebGLDrawBuffers.h>
 #include <LibWeb/WebGL/OpenGLContext.h>
 #include <LibWeb/WebGL/WebGLContextEvent.h>
@@ -93,6 +94,7 @@ void WebGLRenderingContext::visit_edges(Cell::Visitor& visitor)
     visitor.visit(m_canvas_element);
     visitor.visit(m_angle_instanced_arrays_extension);
     visitor.visit(m_oes_vertex_array_object_extension);
+    visitor.visit(m_webgl_compressed_texture_s3tc_extension);
     visitor.visit(m_webgl_draw_buffers_extension);
 }
 
@@ -209,6 +211,15 @@ JS::Object* WebGLRenderingContext::get_extension(String const& name)
         return m_oes_vertex_array_object_extension;
     }
 
+    if (Infra::is_ascii_case_insensitive_match(name, "WEBGL_compressed_texture_s3tc"sv)) {
+        if (!m_webgl_compressed_texture_s3tc_extension) {
+            m_webgl_compressed_texture_s3tc_extension = MUST(Extensions::WebGLCompressedTextureS3tc::create(realm(), this));
+        }
+
+        VERIFY(m_webgl_compressed_texture_s3tc_extension);
+        return m_webgl_compressed_texture_s3tc_extension;
+    }
+
     if (Infra::is_ascii_case_insensitive_match(name, "WEBGL_draw_buffers"sv)) {
         if (!m_webgl_draw_buffers_extension) {
             m_webgl_draw_buffers_extension = MUST(Extensions::WebGLDrawBuffers::create(realm(), *this));

Libraries/LibWeb/WebGL/WebGLRenderingContext.h

@@ -83,6 +83,7 @@ private:
     // "Multiple calls to getExtension with the same extension string, taking into account case-insensitive comparison, must return the same object as long as the extension is enabled."
     GC::Ptr<Extensions::ANGLEInstancedArrays> m_angle_instanced_arrays_extension;
     GC::Ptr<Extensions::OESVertexArrayObject> m_oes_vertex_array_object_extension;
+    GC::Ptr<Extensions::WebGLCompressedTextureS3tc> m_webgl_compressed_texture_s3tc_extension;
     GC::Ptr<Extensions::WebGLDrawBuffers> m_webgl_draw_buffers_extension;
 
     virtual void set_error(GLenum error) override;

Libraries/LibWeb/idl_files.cmake

@@ -388,6 +388,7 @@ libweb_js_bindings(WebAudio/PeriodicWave)
 libweb_js_bindings(WebAudio/StereoPannerNode)
 libweb_js_bindings(WebGL/Extensions/ANGLEInstancedArrays)
 libweb_js_bindings(WebGL/Extensions/OESVertexArrayObject)
+libweb_js_bindings(WebGL/Extensions/WebGLCompressedTextureS3tc)
 libweb_js_bindings(WebGL/Extensions/WebGLDrawBuffers)
 libweb_js_bindings(WebGL/Extensions/WebGLVertexArrayObjectOES)
 libweb_js_bindings(WebGL/WebGL2RenderingContext)

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp

@@ -832,7 +832,7 @@ class @class_name@ : public WebGLRenderingContextBase {
 public:
     @class_name@(JS::Realm&, NonnullOwnPtr<OpenGLContext>);
 
-    OpenGLContext& context() { return *m_context; }
+    virtual OpenGLContext& context() override { return *m_context; }
 
     virtual void present() = 0;
     virtual void needs_to_present() = 0;