From f5336ce7bcc810d7043448f53bdcd03bbbcbbe68 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Wed, 9 May 2018 00:33:25 +0900
Subject: [PATCH] opengl: Use 'EXT' functions for framebuffers

Some pretty old machines don't support OpenGL 3.x or later, and in
such environment, some framebuffer functions like glGenFramebuffers
are not available. Instead, EXT versions can be used even on
machines that don't support OpenGL 3.x.

After this change, Ebiten always tries to use EXT version of
framebuffer functions. I believe EXT version is always available
when non-EXT version is available, so this chang eshould be safe.

Fixes #602
---
 internal/opengl/context_desktop.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/internal/opengl/context_desktop.go b/internal/opengl/context_desktop.go
index 7767b4beb..faaae3fc8 100644
--- a/internal/opengl/context_desktop.go
+++ b/internal/opengl/context_desktop.go
@@ -162,7 +162,7 @@ func (c *Context) NewTexture(width, height int) (Texture, error) {
 
 func (c *Context) bindFramebufferImpl(f Framebuffer) {
 	_ = c.runOnContextThread(func() error {
-		gl.BindFramebuffer(gl.FRAMEBUFFER, uint32(f))
+		gl.BindFramebufferEXT(gl.FRAMEBUFFER, uint32(f))
 		return nil
 	})
 }
@@ -233,7 +233,7 @@ func (c *Context) NewFramebuffer(texture Texture) (Framebuffer, error) {
 	var framebuffer Framebuffer
 	var f uint32
 	if err := c.runOnContextThread(func() error {
-		gl.GenFramebuffers(1, &f)
+		gl.GenFramebuffersEXT(1, &f)
 		// TODO: Use gl.IsFramebuffer
 		if f <= 0 {
 			return errors.New("opengl: creating framebuffer failed: gl.IsFramebuffer returns false")
@@ -244,8 +244,8 @@ func (c *Context) NewFramebuffer(texture Texture) (Framebuffer, error) {
 	}
 	c.bindFramebuffer(Framebuffer(f))
 	if err := c.runOnContextThread(func() error {
-		gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, uint32(texture), 0)
-		s := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
+		gl.FramebufferTexture2DEXT(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, uint32(texture), 0)
+		s := gl.CheckFramebufferStatusEXT(gl.FRAMEBUFFER)
 		if s != gl.FRAMEBUFFER_COMPLETE {
 			if s != 0 {
 				return fmt.Errorf("opengl: creating framebuffer failed: %v", s)
@@ -273,7 +273,7 @@ func (c *Context) setViewportImpl(width, height int) {
 func (c *Context) DeleteFramebuffer(f Framebuffer) {
 	_ = c.runOnContextThread(func() error {
 		ff := uint32(f)
-		if !gl.IsFramebuffer(ff) {
+		if !gl.IsFramebufferEXT(ff) {
 			return nil
 		}
 		if c.lastFramebuffer == f {
@@ -281,7 +281,7 @@ func (c *Context) DeleteFramebuffer(f Framebuffer) {
 			c.lastViewportWidth = 0
 			c.lastViewportHeight = 0
 		}
-		gl.DeleteFramebuffers(1, &ff)
+		gl.DeleteFramebuffersEXT(1, &ff)
 		return nil
 	})
 }