Auto merge of #21129 - servo:webgl, r=emilio

Implement instanced WebGL drawing calls (part of #20791)

This is half of #20599. The check for drawElements is a bit more complex to implement.

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3 files changed, 123 insertions, 1 deletions

diff --git a/components/script/dom/webgl_extensions/ext/angleinstancedarrays.rs b/components/script/dom/webgl_extensions/ext/angleinstancedarrays.rs
new file mode 100644
index 00000000000..f35abaf15af
--- /dev/null
+++ b/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);
+    }
+}
diff --git a/components/script/dom/webgl_extensions/ext/mod.rs b/components/script/dom/webgl_extensions/ext/mod.rs
index bdf19d5327a..62f75cb048a 100644
--- a/components/script/dom/webgl_extensions/ext/mod.rs
+++ b/components/script/dom/webgl_extensions/ext/mod.rs
@@ -5,6 +5,7 @@
 use dom::bindings::codegen::Bindings::WebGLRenderingContextBinding::WebGLRenderingContextConstants as constants;
 use super::{ext_constants, WebGLExtension, WebGLExtensions, WebGLExtensionSpec};
 
+pub mod angleinstancedarrays;
 pub mod extblendminmax;
 pub mod extshadertexturelod;
 pub mod exttexturefilteranisotropic;
diff --git a/components/script/dom/webgl_extensions/extensions.rs b/components/script/dom/webgl_extensions/extensions.rs
index c5413ea1eb2..b3812f51cf5 100644
--- a/components/script/dom/webgl_extensions/extensions.rs
+++ b/components/script/dom/webgl_extensions/extensions.rs
@@ -4,6 +4,7 @@
 
 use canvas_traits::webgl::{WebGLError, WebGLVersion};
 use dom::bindings::cell::DomRefCell;
+use dom::bindings::codegen::Bindings::ANGLEInstancedArraysBinding::ANGLEInstancedArraysConstants;
 use dom::bindings::codegen::Bindings::EXTTextureFilterAnisotropicBinding::EXTTextureFilterAnisotropicConstants;
 use dom::bindings::codegen::Bindings::OESStandardDerivativesBinding::OESStandardDerivativesConstants;
 use dom::bindings::codegen::Bindings::OESTextureHalfFloatBinding::OESTextureHalfFloatConstants;
@@ -54,6 +55,13 @@ const DEFAULT_DISABLED_GET_TEX_PARAMETER_NAMES_WEBGL1: [GLenum; 1] = [
     EXTTextureFilterAnisotropicConstants::TEXTURE_MAX_ANISOTROPY_EXT,
 ];
 
+// Param names that are implemented for glGetVertexAttrib in a WebGL 1.0 context
+// but must trigger a InvalidEnum error until the related WebGL Extensions are enabled.
+// Example: https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays/
+const DEFAULT_DISABLED_GET_VERTEX_ATTRIB_NAMES_WEBGL1: [GLenum; 1] = [
+    ANGLEInstancedArraysConstants::VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE,
+];
+
 /// WebGL features that are enabled/disabled by WebGL Extensions.
 #[derive(JSTraceable, MallocSizeOf)]
 struct WebGLExtensionFeatures {
@@ -68,6 +76,8 @@ struct WebGLExtensionFeatures {
     disabled_get_parameter_names: FnvHashSet<GLenum>,
     /// WebGL GetTexParameter() names enabled by extensions.
     disabled_get_tex_parameter_names: FnvHashSet<GLenum>,
+    /// WebGL GetAttribVertex() names enabled by extensions.
+    disabled_get_vertex_attrib_names: FnvHashSet<GLenum>,
     /// WebGL OES_element_index_uint extension.
     element_index_uint_enabled: bool,
     /// WebGL EXT_blend_minmax extension.
@@ -80,6 +90,7 @@ impl WebGLExtensionFeatures {
             disabled_tex_types,
             disabled_get_parameter_names,
             disabled_get_tex_parameter_names,
+            disabled_get_vertex_attrib_names,
             element_index_uint_enabled,
             blend_minmax_enabled,
         ) = match webgl_version {
@@ -88,12 +99,20 @@ impl WebGLExtensionFeatures {
                     DEFAULT_DISABLED_TEX_TYPES_WEBGL1.iter().cloned().collect(),
                     DEFAULT_DISABLED_GET_PARAMETER_NAMES_WEBGL1.iter().cloned().collect(),
                     DEFAULT_DISABLED_GET_TEX_PARAMETER_NAMES_WEBGL1.iter().cloned().collect(),
+                    DEFAULT_DISABLED_GET_VERTEX_ATTRIB_NAMES_WEBGL1.iter().cloned().collect(),
                     false,
                     false,
                 )
             },
             WebGLVersion::WebGL2 => {
-                (Default::default(), Default::default(), Default::default(), true, true)
+                (
+                    Default::default(),
+                    Default::default(),
+                    Default::default(),
+                    Default::default(),
+                    true,
+                    true,
+                )
             }
         };
         Self {
@@ -105,6 +124,7 @@ impl WebGLExtensionFeatures {
             hint_targets: Default::default(),
             disabled_get_parameter_names,
             disabled_get_tex_parameter_names,
+            disabled_get_vertex_attrib_names,
             element_index_uint_enabled,
             blend_minmax_enabled,
         }
@@ -269,7 +289,16 @@ impl WebGLExtensions {
         !self.features.borrow().disabled_get_tex_parameter_names.contains(&name)
     }
 
+    pub fn enable_get_vertex_attrib_name(&self, name: GLenum) {
+        self.features.borrow_mut().disabled_get_vertex_attrib_names.remove(&name);
+    }
+
+    pub fn is_get_vertex_attrib_name_enabled(&self, name: GLenum) -> bool {
+        !self.features.borrow().disabled_get_vertex_attrib_names.contains(&name)
+    }
+
     fn register_all_extensions(&self) {
+        self.register::<ext::angleinstancedarrays::ANGLEInstancedArrays>();
         self.register::<ext::extblendminmax::EXTBlendMinmax>();
         self.register::<ext::extshadertexturelod::EXTShaderTextureLod>();
         self.register::<ext::exttexturefilteranisotropic::EXTTextureFilterAnisotropic>();