From a718992acbcc344bcc4cd7d6722effc230535ddd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Capucho?= <jcapucho7@gmail.com>
Date: Mon, 19 Oct 2020 14:40:30 +0100
Subject: [PATCH] Added new external functions to the glsl backend to make it
 on par with the typifier (#240)

---
 README.md        |  2 +-
 src/back/glsl.rs | 35 ++++++++++++++---------------------
 2 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/README.md b/README.md
index d0672f6362..e09db9182a 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ SPIR-V (binary) | :construction:     |       |
 WGSL            |                    |       |
 Metal           | :construction:     |       |
 HLSL            |                    |       |
-GLSL            |                    |       |
+GLSL            | :construction:     |       |
 AIR             |                    |       |
 DXIR            |                    |       |
 DXIL            |                    |       |
diff --git a/src/back/glsl.rs b/src/back/glsl.rs
index 3884282a5e..c4cb2c340b 100644
--- a/src/back/glsl.rs
+++ b/src/back/glsl.rs
@@ -1245,17 +1245,22 @@ fn write_expression<'a, 'b>(
             origin: crate::FunctionOrigin::External(ref name),
             ref arguments,
         } => match name.as_str() {
-            "cos" | "normalize" | "sin" => {
+            "cos" | "normalize" | "sin" | "length" | "abs" | "floor" | "inverse" => {
                 let expr = write_expression(&builder.expressions[arguments[0]], module, builder)?;
 
                 Cow::Owned(format!("{}({})", name, expr))
             }
-            "fclamp" => {
-                let val = write_expression(&builder.expressions[arguments[0]], module, builder)?;
-                let min = write_expression(&builder.expressions[arguments[1]], module, builder)?;
-                let max = write_expression(&builder.expressions[arguments[2]], module, builder)?;
+            "fclamp" | "clamp" | "mix" | "smoothstep" => {
+                let x = write_expression(&builder.expressions[arguments[0]], module, builder)?;
+                let y = write_expression(&builder.expressions[arguments[1]], module, builder)?;
+                let a = write_expression(&builder.expressions[arguments[2]], module, builder)?;
 
-                Cow::Owned(format!("clamp({}, {}, {})", val, min, max))
+                let name = match name.as_str() {
+                    "fclamp" => "clamp",
+                    name => name,
+                };
+
+                Cow::Owned(format!("{}({}, {}, {})", name, x, y, a))
             }
             "atan2" => {
                 let x = write_expression(&builder.expressions[arguments[0]], module, builder)?;
@@ -1263,23 +1268,11 @@ fn write_expression<'a, 'b>(
 
                 Cow::Owned(format!("atan({}, {})", y, x))
             }
-            "distance" => {
-                let p0 = write_expression(&builder.expressions[arguments[0]], module, builder)?;
-                let p1 = write_expression(&builder.expressions[arguments[1]], module, builder)?;
-
-                Cow::Owned(format!("distance({}, {})", p0, p1))
-            }
-            "length" => {
+            "distance" | "dot" | "min" | "max" | "reflect" | "pow" | "step" | "cross" => {
                 let x = write_expression(&builder.expressions[arguments[0]], module, builder)?;
+                let y = write_expression(&builder.expressions[arguments[1]], module, builder)?;
 
-                Cow::Owned(format!("length({})", x))
-            }
-            "mix" => {
-                let x = write_expression(&builder.expressions[arguments[0]], module, builder)?;
-                let y = write_expression(&builder.expressions[arguments[0]], module, builder)?;
-                let a = write_expression(&builder.expressions[arguments[0]], module, builder)?;
-
-                Cow::Owned(format!("mix({}, {}, {})", x, y, a))
+                Cow::Owned(format!("{}({}, {})", name, x, y))
             }
             other => {
                 return Err(Error::Custom(format!(