From c9bc5913fd93f40e4d1d51a1b82051df5e68c2ed Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 6 Dec 2019 08:42:52 +0900
Subject: [PATCH] driver: Refactoring: Remove Graphics.Flush

Updates #226
---
 internal/driver/graphics.go              | 1 -
 internal/graphicscommand/command.go      | 4 ----
 internal/graphicsdriver/metal/driver.go  | 4 ----
 internal/graphicsdriver/opengl/driver.go | 8 +++-----
 4 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/internal/driver/graphics.go b/internal/driver/graphics.go
index dd7288e86..41afbedf3 100644
--- a/internal/driver/graphics.go
+++ b/internal/driver/graphics.go
@@ -28,7 +28,6 @@ type Graphics interface {
 	SetWindow(window unsafe.Pointer)
 	SetTransparent(transparent bool)
 	SetVertices(vertices []float32, indices []uint16)
-	Flush()
 	NewImage(width, height int) (Image, error)
 	NewScreenFramebufferImage(width, height int) (Image, error)
 	Reset() error
diff --git a/internal/graphicscommand/command.go b/internal/graphicscommand/command.go
index 62cd2fc1a..2d03b7a4d 100644
--- a/internal/graphicscommand/command.go
+++ b/internal/graphicscommand/command.go
@@ -274,10 +274,6 @@ func (q *commandQueue) Flush() {
 			// introduced than drawTrianglesCommand.
 			indexOffset += c.NumIndices()
 		}
-		if 0 < nc {
-			// Call glFlush to prevent black flicking (especially on Android (#226) and iOS).
-			theGraphicsDriver.Flush()
-		}
 		cs = cs[nc:]
 	}
 	theGraphicsDriver.End()
diff --git a/internal/graphicsdriver/metal/driver.go b/internal/graphicsdriver/metal/driver.go
index 11553f791..ed0a8ab49 100644
--- a/internal/graphicsdriver/metal/driver.go
+++ b/internal/graphicsdriver/metal/driver.go
@@ -364,10 +364,6 @@ func (d *Driver) SetVertices(vertices []float32, indices []uint16) {
 	})
 }
 
-func (d *Driver) Flush() {
-	// On Metal, flushing command buffers only once is enough except for manipulating pixels. Do not call flush.
-}
-
 func (d *Driver) flush(wait bool, present bool) {
 	d.t.Call(func() error {
 		if d.cb == (mtl.CommandBuffer{}) {
diff --git a/internal/graphicsdriver/opengl/driver.go b/internal/graphicsdriver/opengl/driver.go
index c80421e0b..76bfa3576 100644
--- a/internal/graphicsdriver/opengl/driver.go
+++ b/internal/graphicsdriver/opengl/driver.go
@@ -47,7 +47,9 @@ func (d *Driver) Begin() {
 }
 
 func (d *Driver) End() {
-	// Do nothing.
+	// Call glFlush to prevent black flicking (especially on Android (#226) and iOS).
+	// TODO: examples/sprites worked without this. Is this really needed?
+	d.context.flush()
 }
 
 func (d *Driver) SetWindow(window unsafe.Pointer) {
@@ -128,10 +130,6 @@ func (d *Driver) Draw(indexLen int, indexOffset int, mode driver.CompositeMode,
 	return nil
 }
 
-func (d *Driver) Flush() {
-	d.context.flush()
-}
-
 func (d *Driver) SetVsyncEnabled(enabled bool) {
 	// Do nothing
 }