From 922f3925446aad51426e7284d25d84b844c6595b Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Wed, 24 Feb 2016 22:56:47 +0900
Subject: [PATCH] ui: Bug fix: Call glFinish before glfwSwapBuffers to make
 sure all OpenGL tasks are executed (#161)

---
 internal/graphics/opengl/context.go | 4 ++++
 internal/ui/ui_glfw.go              | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/internal/graphics/opengl/context.go b/internal/graphics/opengl/context.go
index ec2eee1f1..78049c6d3 100644
--- a/internal/graphics/opengl/context.go
+++ b/internal/graphics/opengl/context.go
@@ -336,3 +336,7 @@ func (c *Context) BufferSubData(bufferType BufferType, data []int16) {
 func (c *Context) DrawElements(mode Mode, len int) {
 	gl.DrawElements(mgl.Enum(mode), len, mgl.UNSIGNED_SHORT, 0)
 }
+
+func (c *Context) Finish() {
+	gl.Finish()
+}
diff --git a/internal/ui/ui_glfw.go b/internal/ui/ui_glfw.go
index 663edf998..55b8381c0 100644
--- a/internal/ui/ui_glfw.go
+++ b/internal/ui/ui_glfw.go
@@ -147,6 +147,9 @@ func (u *userInterface) isClosed() bool {
 }
 
 func (u *userInterface) swapBuffers() {
+	// Call glFinish before glfwSwapBuffer to make sure
+	// all OpenGL tasks are executed.
+	u.context.Finish()
 	u.context.RunOnContextThread(func() {
 		u.window.SwapBuffers()
 	})