Implement instanced WebGL drawing calls (part of #20791)

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

@@ -0,0 +1,92 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+use canvas_traits::webgl::WebGLVersion;
+use dom::bindings::codegen::Bindings::ANGLEInstancedArraysBinding;
+use dom::bindings::codegen::Bindings::ANGLEInstancedArraysBinding::ANGLEInstancedArraysConstants;
+use dom::bindings::codegen::Bindings::ANGLEInstancedArraysBinding::ANGLEInstancedArraysMethods;
+use dom::bindings::reflector::{DomObject, Reflector, reflect_dom_object};
+use dom::bindings::root::{Dom, DomRoot};
+use dom::webglrenderingcontext::WebGLRenderingContext;
+use dom_struct::dom_struct;
+use super::{WebGLExtension, WebGLExtensions, WebGLExtensionSpec};
+
+#[dom_struct]
+pub struct ANGLEInstancedArrays {
+    reflector_: Reflector,
+    ctx: Dom<WebGLRenderingContext>,
+}
+
+impl ANGLEInstancedArrays {
+    fn new_inherited(ctx: &WebGLRenderingContext) -> Self {
+        Self {
+            reflector_: Reflector::new(),
+            ctx: Dom::from_ref(ctx),
+        }
+    }
+}
+
+impl WebGLExtension for ANGLEInstancedArrays {
+    type Extension = Self;
+
+    fn new(ctx: &WebGLRenderingContext) -> DomRoot<Self> {
+        reflect_dom_object(
+            Box::new(ANGLEInstancedArrays::new_inherited(ctx)),
+            &*ctx.global(),
+            ANGLEInstancedArraysBinding::Wrap,
+        )
+    }
+
+    fn spec() -> WebGLExtensionSpec {
+        WebGLExtensionSpec::Specific(WebGLVersion::WebGL1)
+    }
+
+    fn is_supported(ext: &WebGLExtensions) -> bool {
+        ext.supports_any_gl_extension(&[
+            "GL_ANGLE_instanced_arrays",
+            "GL_ARB_instanced_arrays",
+            "GL_EXT_instanced_arrays",
+            "GL_NV_instanced_arrays",
+        ])
+    }
+
+    fn enable(ext: &WebGLExtensions) {
+        ext.enable_get_vertex_attrib_name(
+            ANGLEInstancedArraysConstants::VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE,
+        );
+    }
+
+    fn name() -> &'static str {
+        "ANGLE_instanced_arrays"
+    }
+}
+
+impl ANGLEInstancedArraysMethods for ANGLEInstancedArrays {
+    // https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays/
+    fn DrawArraysInstancedANGLE(
+        &self,
+        mode: u32,
+        first: i32,
+        count: i32,
+        primcount: i32,
+    ) {
+        self.ctx.draw_arrays_instanced(mode, first, count, primcount);
+    }
+
+    // https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays/
+    fn DrawElementsInstancedANGLE(
+        &self,
+        mode: u32,
+        count: i32,
+        type_: u32,
+        offset: i64,
+        primcount: i32,
+    ) {
+        self.ctx.draw_elements_instanced(mode, count, type_, offset, primcount);
+    }
+
+    fn VertexAttribDivisorANGLE(&self, index: u32, divisor: u32) {
+        self.ctx.vertex_attrib_divisor(index, divisor);
+    }
+}