Implement EXT_frag_depth

components/script/dom/webgl_extensions/ext/extfragdepth.rs

@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use super::{WebGLExtension, WebGLExtensionSpec, WebGLExtensions};
+use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::webglrenderingcontext::WebGLRenderingContext;
+use canvas_traits::webgl::{WebGLSLVersion, WebGLVersion};
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct EXTFragDepth {
+    reflector_: Reflector,
+}
+
+impl EXTFragDepth {
+    fn new_inherited() -> EXTFragDepth {
+        Self {
+            reflector_: Reflector::new(),
+        }
+    }
+}
+
+impl WebGLExtension for EXTFragDepth {
+    type Extension = Self;
+
+    fn new(ctx: &WebGLRenderingContext) -> DomRoot<Self> {
+        reflect_dom_object(Box::new(Self::new_inherited()), &*ctx.global())
+    }
+
+    fn spec() -> WebGLExtensionSpec {
+        WebGLExtensionSpec::Specific(WebGLVersion::WebGL1)
+    }
+
+    fn is_supported(ext: &WebGLExtensions) -> bool {
+        let min_glsl_version = if ext.is_gles() {
+            WebGLSLVersion { major: 3, minor: 0 }
+        } else {
+            WebGLSLVersion {
+                major: 1,
+                minor: 10,
+            }
+        };
+        match (
+            ext.is_gles(),
+            ext.is_min_glsl_version_satisfied(min_glsl_version),
+        ) {
+            // ANGLE's shader translator can't translate ESSL1 exts to ESSL3. (bug
+            // 1524804)
+            (true, true) => false,
+            (true, false) => ext.supports_gl_extension("GL_EXT_frag_depth"),
+            (false, is_min_glsl_version_satisfied) => is_min_glsl_version_satisfied,
+        }
+    }
+
+    fn enable(_ext: &WebGLExtensions) {}
+
+    fn name() -> &'static str {
+        "EXT_frag_depth"
+    }
+}