From 75d34ab585a06ab2210ac1a9fee48c7bc1d914d0 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Thu, 23 Jul 2020 19:15:34 +0900
Subject: [PATCH] graphicsdriver/opengl: Forbids PBO on Raspberry Pi 4 (#1261)

Fixes #1208
---
 .../graphicsdriver/opengl/context_desktop.go  | 16 ++++++-
 .../graphicsdriver/opengl/context_notx.go     | 21 +++++++++
 internal/graphicsdriver/opengl/context_x.go   | 46 +++++++++++++++++++
 .../graphicsdriver/opengl/gl/package_x.go     | 32 +++++++++++++
 4 files changed, 113 insertions(+), 2 deletions(-)
 create mode 100644 internal/graphicsdriver/opengl/context_notx.go
 create mode 100644 internal/graphicsdriver/opengl/context_x.go
 create mode 100644 internal/graphicsdriver/opengl/gl/package_x.go

diff --git a/internal/graphicsdriver/opengl/context_desktop.go b/internal/graphicsdriver/opengl/context_desktop.go
index 06b35108d..08b23d9e0 100644
--- a/internal/graphicsdriver/opengl/context_desktop.go
+++ b/internal/graphicsdriver/opengl/context_desktop.go
@@ -546,11 +546,23 @@ func (c *context) needsRestoring() bool {
 }
 
 func (c *context) canUsePBO() bool {
-	return true
+	var available bool
+	_ = c.t.Call(func() error {
+		available = isPBOAvailable()
+		return nil
+	})
+
+	return available
 }
 
 func (c *context) texSubImage2D(t textureNative, width, height int, args []*driver.ReplacePixelsArgs) {
-	panic("opengl: texSubImage2D is not implemented on this environment")
+	c.bindTexture(t)
+	_ = c.t.Call(func() error {
+		for _, a := range args {
+			gl.TexSubImage2D(gl.TEXTURE_2D, 0, int32(a.X), int32(a.Y), int32(a.Width), int32(a.Height), gl.RGBA, gl.UNSIGNED_BYTE, gl.Ptr(a.Pixels))
+		}
+		return nil
+	})
 }
 
 func (c *context) newPixelBufferObject(width, height int) buffer {
diff --git a/internal/graphicsdriver/opengl/context_notx.go b/internal/graphicsdriver/opengl/context_notx.go
new file mode 100644
index 000000000..0521c85d5
--- /dev/null
+++ b/internal/graphicsdriver/opengl/context_notx.go
@@ -0,0 +1,21 @@
+// Copyright 2020 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build js !freebsd,!linux
+
+package opengl
+
+func isPBOAvailable() bool {
+	return true
+}
diff --git a/internal/graphicsdriver/opengl/context_x.go b/internal/graphicsdriver/opengl/context_x.go
new file mode 100644
index 000000000..60f4b0970
--- /dev/null
+++ b/internal/graphicsdriver/opengl/context_x.go
@@ -0,0 +1,46 @@
+// Copyright 2020 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !js
+// +build freebsd linux
+
+package opengl
+
+import (
+	"strings"
+	"sync"
+
+	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/opengl/gl"
+)
+
+var (
+	pboAvailable     = true
+	pboAvailableOnce sync.Once
+)
+
+func isPBOAvailable() bool {
+	pboAvailableOnce.Do(func() {
+		// This must be called after GL context is created.
+		str := gl.RendererDeviceString()
+		tokens := strings.Split(str, " ")
+		if len(tokens) == 0 {
+			return
+		}
+		// Raspbery Pi 4 has an issue around PBO (#1208).
+		if tokens[0] == "V3D" {
+			pboAvailable = false
+		}
+	})
+	return pboAvailable
+}
diff --git a/internal/graphicsdriver/opengl/gl/package_x.go b/internal/graphicsdriver/opengl/gl/package_x.go
new file mode 100644
index 000000000..26c2a9c97
--- /dev/null
+++ b/internal/graphicsdriver/opengl/gl/package_x.go
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: MIT
+
+// +build !js
+// +build freebsd linux
+
+package gl
+
+// #include <GL/glx.h>
+//
+// static const char* RendererDeviceString() {
+// #ifdef GLX_MESA_query_renderer
+//   static PFNGLXQUERYCURRENTRENDERERSTRINGMESAPROC queryString;
+//   if (!queryString) {
+//     queryString = (PFNGLXQUERYCURRENTRENDERERSTRINGMESAPROC)
+//       glXGetProcAddressARB((const GLubyte *)"glXQueryCurrentRendererStringMESA");
+//   }
+//
+//   static const char* rendererDevice;
+//   if (!rendererDevice) {
+//     rendererDevice = queryString(GLX_RENDERER_DEVICE_ID_MESA);
+//   }
+//
+//   return rendererDevice;
+// #else
+//   return "";
+// #endif
+// }
+import "C"
+
+func RendererDeviceString() string {
+	return C.GoString(C.RendererDeviceString())
+}