From 15272d2c3b4683c97ac44065429360016bae998b Mon Sep 17 00:00:00 2001
From: Anthony Ramine <n.oxyde@gmail.com>
Date: Wed, 4 Apr 2018 15:43:09 +0200
Subject: [PATCH] Properly allow FUNC_SUBTRACT and FUNC_REVERSE_SUBTRACT in
 blendEquation

---
 components/script/dom/webglrenderingcontext.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index b0b91a71f77..612a62602ef 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -1477,11 +1477,14 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
     fn BlendEquation(&self, mode: u32) {
-        if mode != constants::FUNC_ADD {
-            return self.webgl_error(InvalidEnum);
+        match mode {
+            constants::FUNC_ADD |
+            constants::FUNC_SUBTRACT |
+            constants::FUNC_REVERSE_SUBTRACT => {
+                self.send_command(WebGLCommand::BlendEquation(mode))
+            },
+            _ => self.webgl_error(InvalidEnum)
         }
-
-        self.send_command(WebGLCommand::BlendEquation(mode));
     }
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3