From 5de862b4d175578ed67e177d482ac31bf811d486 Mon Sep 17 00:00:00 2001
From: natrixaeria <janng@gmx.de>
Date: Thu, 13 Jun 2019 01:34:35 +0200
Subject: Create a WebGl2 context

---
 webhogg/wasm/Cargo.toml              |  3 +++
 webhogg/wasm/src/context/graphics.rs | 18 +++++++++++++++++-
 webhogg/wasm/src/error.rs            |  6 +++---
 webhogg/wasm/src/graphics.rs         |  4 ++--
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/webhogg/wasm/Cargo.toml b/webhogg/wasm/Cargo.toml
index 71b6a8e..2d69f41 100644
--- a/webhogg/wasm/Cargo.toml
+++ b/webhogg/wasm/Cargo.toml
@@ -18,8 +18,11 @@ lto = true
 wasm-bindgen = "0.2"
 log = "0.4"
 fern = "0.5"
+js-sys = "0.3"
 
 [dependencies.web-sys]
 version = "0.3"
 features = [
+    "OffscreenCanvas",
+    "WebGl2RenderingContext"
 ]
diff --git a/webhogg/wasm/src/context/graphics.rs b/webhogg/wasm/src/context/graphics.rs
index 57955d0..3476e5d 100644
--- a/webhogg/wasm/src/context/graphics.rs
+++ b/webhogg/wasm/src/context/graphics.rs
@@ -1,10 +1,26 @@
+use log::*;
 use crate::error::WasmError;
+use wasm_bindgen::JsCast;
+use web_sys::WebGl2RenderingContext as Gl;
 
 pub struct GraphicsContext {
 }
 
 impl GraphicsContext {
-    pub fn from_canvas() -> Result<Self, WasmError> {
+    pub fn from_canvas(canvas: web_sys::OffscreenCanvas) -> Result<Self, WasmError> {
+        let context = canvas.get_context("webgl2")
+            .map_err(|_| WasmError::WebGl2ContextCreation(
+                    format!("context cration failed: getContext returned an exception")))?
+            .ok_or_else(|| WasmError::WebGl2ContextCreation(
+                    format!("context cration failed: getContext returned nothing")))?;
+        let context = context
+            .dyn_into::<Gl>()
+            .map_err(|_| WasmError::WebGl2ContextCreation(
+                    format!("context object is not a context")))?;
+
+        //context.clear(Gl::COLOR_BUFFER_BIT);
+        //context.clear_color(0.6, 0.0, 0.6, 1.0);
+            
         Ok(Self {
         })
     }
diff --git a/webhogg/wasm/src/error.rs b/webhogg/wasm/src/error.rs
index b544112..1c6ec27 100644
--- a/webhogg/wasm/src/error.rs
+++ b/webhogg/wasm/src/error.rs
@@ -2,7 +2,7 @@ use std::error::Error;
 
 #[derive(Debug)]
 pub enum WasmError {
-    TestError(String),
+    WebGl2ContextCreation(String),
 }
 
 impl std::fmt::Display for WasmError {
@@ -14,7 +14,7 @@ impl std::fmt::Display for WasmError {
 impl Error for WasmError {
     fn description(&self) -> &str {
         match self {
-            WasmError::TestError(msg) => msg,
+            WasmError::WebGl2ContextCreation(msg) => msg,
         }
     }
 
@@ -24,7 +24,7 @@ impl Error for WasmError {
 impl WasmError {
     pub fn name(&self) -> &str {
         match self {
-            WasmError::TestError(_) => "TestError",
+            WasmError::WebGl2ContextCreation(_) => "WebGl2ContextCreationError",
         }
     }
 }
diff --git a/webhogg/wasm/src/graphics.rs b/webhogg/wasm/src/graphics.rs
index 8169a3c..a879c5e 100644
--- a/webhogg/wasm/src/graphics.rs
+++ b/webhogg/wasm/src/graphics.rs
@@ -3,11 +3,11 @@ use log::*;
 use crate::*;
 
 #[wasm_bindgen]
-pub fn start_graphics() {
+pub fn start_graphics(canvas: web_sys::OffscreenCanvas) {
     logger::init_logger();
     info!("graphics: wasm entry-point reached");
 
-    match context::graphics::GraphicsContext::from_canvas() {
+    match context::graphics::GraphicsContext::from_canvas(canvas) {
         Ok(ctx) => context::set_graphics(ctx),
         Err(e) => error!("graphics {}", e)
     }
-- 
cgit v1.2.3-54-g00ecf