Add support for the EGL_KHR_create_context_no_error extension

4 files changed, 64 insertions, 22 deletions

diff --git a/src/api/egl/mod.rs b/src/api/egl/mod.rs
index 07c70b0..1a6cc06 100644
--- a/src/api/egl/mod.rs
+++ b/src/api/egl/mod.rs
@@ -349,7 +349,7 @@ unsafe fn create_context(egl: &ffi::egl::Egl, display: ffi::egl::types::EGLDispl
         format!("")
     };
 
-    let mut context_attributes = vec![];
+    let mut context_attributes = Vec::with_capacity(10);
     let mut flags = 0;
 
     if egl_version >= &(1, 5) ||
@@ -361,30 +361,62 @@ unsafe fn create_context(egl: &ffi::egl::Egl, display: ffi::egl::types::EGLDispl
         context_attributes.push(ffi::egl::CONTEXT_MINOR_VERSION as i32);
         context_attributes.push(version.1 as i32);
 
-        if egl_version >= &(1, 5) ||
-           extensions.contains("EGL_EXT_create_context_robustness ") ||
-           extensions.ends_with("EGL_EXT_create_context_robustness")
-        {
-            match gl_robustness {
-                Robustness::RobustNoResetNotification | Robustness::TryRobustNoResetNotification => {
-                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY as libc::c_int);
+        // handling robustness
+        let supports_robustness = egl_version >= &(1, 5) ||
+                                  extensions.contains("EGL_EXT_create_context_robustness ") ||
+                                  extensions.ends_with("EGL_EXT_create_context_robustness");
+
+        match gl_robustness {
+            Robustness::NotRobust => (),
+
+            Robustness::NoError => {
+                if extensions.contains("EGL_KHR_create_context_no_error ") ||
+                   extensions.ends_with("EGL_KHR_create_context_no_error")
+                {
+                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_NO_ERROR_KHR as libc::c_int);
+                    context_attributes.push(1);
+                }
+            },
+
+            Robustness::RobustNoResetNotification => {
+                if supports_robustness {
+                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY
+                                            as libc::c_int);
                     context_attributes.push(ffi::egl::NO_RESET_NOTIFICATION as libc::c_int);
                     flags = flags | ffi::egl::CONTEXT_OPENGL_ROBUST_ACCESS as libc::c_int;
-                },
-                Robustness::RobustLoseContextOnReset | Robustness::TryRobustLoseContextOnReset => {
-                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY as libc::c_int);
+                } else {
+                    return Err(CreationError::NotSupported);
+                }
+            },
+
+            Robustness::TryRobustNoResetNotification => {
+                if supports_robustness {
+                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY
+                                            as libc::c_int);
+                    context_attributes.push(ffi::egl::NO_RESET_NOTIFICATION as libc::c_int);
+                    flags = flags | ffi::egl::CONTEXT_OPENGL_ROBUST_ACCESS as libc::c_int;
+                }
+            },
+
+            Robustness::RobustLoseContextOnReset => {
+                if supports_robustness {
+                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY
+                                            as libc::c_int);
                     context_attributes.push(ffi::egl::LOSE_CONTEXT_ON_RESET as libc::c_int);
                     flags = flags | ffi::egl::CONTEXT_OPENGL_ROBUST_ACCESS as libc::c_int;
-                },
-                Robustness::NotRobust => ()
-            }
-        } else {
-            match gl_robustness {
-                Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
+                } else {
                     return Err(CreationError::NotSupported);
-                },
-                _ => ()
-            }
+                }
+            },
+
+            Robustness::TryRobustLoseContextOnReset => {
+                if supports_robustness {
+                    context_attributes.push(ffi::egl::CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY
+                                            as libc::c_int);
+                    context_attributes.push(ffi::egl::LOSE_CONTEXT_ON_RESET as libc::c_int);
+                    flags = flags | ffi::egl::CONTEXT_OPENGL_ROBUST_ACCESS as libc::c_int;
+                }
+            },
         }
 
         if gl_debug {
@@ -400,6 +432,7 @@ unsafe fn create_context(egl: &ffi::egl::Egl, display: ffi::egl::types::EGLDispl
         context_attributes.push(flags);
 
     } else if egl_version >= &(1, 3) && api == Api::OpenGlEs {
+        // robustness is not supported
         match gl_robustness {
             Robustness::RobustNoResetNotification | Robustness::RobustLoseContextOnReset => {
                 return Err(CreationError::NotSupported);
diff --git a/src/api/glx/mod.rs b/src/api/glx/mod.rs
index 2c15e18..d286813 100644
--- a/src/api/glx/mod.rs
+++ b/src/api/glx/mod.rs
@@ -246,7 +246,8 @@ fn create_context(glx: &ffi::glx::Glx, extra_functions: &ffi::glx_extra::Glx, ex
                             attributes.push(ffi::glx_extra::LOSE_CONTEXT_ON_RESET_ARB as libc::c_int);
                             flags = flags | ffi::glx_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as libc::c_int;
                         },
-                        Robustness::NotRobust => ()
+                        Robustness::NotRobust => (),
+                        Robustness::NoError => (),
                     }
                 } else {
                     match robustness {
diff --git a/src/api/wgl/mod.rs b/src/api/wgl/mod.rs
index ee8aa3b..7a1ab3a 100644
--- a/src/api/wgl/mod.rs
+++ b/src/api/wgl/mod.rs
@@ -283,7 +283,8 @@ unsafe fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'st
                             attributes.push(gl::wgl_extra::LOSE_CONTEXT_ON_RESET_ARB as libc::c_int);
                             flags = flags | gl::wgl_extra::CONTEXT_ROBUST_ACCESS_BIT_ARB as libc::c_int;
                         },
-                        Robustness::NotRobust => ()
+                        Robustness::NotRobust => (),
+                        Robustness::NoError => (),
                     }
                 } else {
                     match builder.gl_robustness {
diff --git a/src/lib.rs b/src/lib.rs
index 64b0ace..3dcf0f9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -205,6 +205,13 @@ pub enum Robustness {
     /// shaders.
     NotRobust,
 
+    /// The driver doesn't check anything. This option is very dangerous. Please know what you're
+    /// doing before using it. See the `GL_KHR_no_error` extension.
+    ///
+    /// Since this option is purely an optimisation, no error will be returned if the backend
+    /// doesn't support it. Instead it will automatically fall back to `NotRobust`.
+    NoError,
+
     /// Everything is checked to avoid any crash. The driver will attempt to avoid any problem,
     /// but if a problem occurs the behavior is implementation-defined. You are just guaranteed not
     /// to get a crash.