From: Carl Hetherington <cth@carlh.net>
Date: Mon, 25 Nov 2019 20:24:03 +0000 (+0100)
Subject: Use glTexSubImage2D when possible, as suggested by https://www.khronos.org/opengl... 
X-Git-Tag: v2.15.40^2~4
X-Git-Url: https://main.carlh.net/gitweb/?p=dcpomatic.git;a=commitdiff_plain;h=4f0575fcb518d959e8dcf581ec8181609782b4ef

Use glTexSubImage2D when possible, as suggested by https://khronos.org/opengl/wiki/Common_Mistakes
---

diff --git a/src/wx/gl_video_view.cc b/src/wx/gl_video_view.cc
index a461939a7..d47ad87f4 100644
--- a/src/wx/gl_video_view.cc
+++ b/src/wx/gl_video_view.cc
@@ -55,6 +55,7 @@ using boost::optional;
 
 GLVideoView::GLVideoView (FilmViewer* viewer, wxWindow *parent)
 	: VideoView (viewer)
+	, _have_storage (false)
 	, _vsync_enabled (false)
 	, _thread (0)
 	, _playing (false)
@@ -264,11 +265,21 @@ GLVideoView::set_image (shared_ptr<const Image> image)
 	DCPOMATIC_ASSERT (image->pixel_format() == AV_PIX_FMT_RGB24);
 	DCPOMATIC_ASSERT (!image->aligned());
 
+	if (image->size() != _size) {
+		_have_storage = false;
+	}
+
 	_size = image->size ();
 	glPixelStorei (GL_UNPACK_ALIGNMENT, 1);
 	check_gl_error ("glPixelStorei");
-	glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB8, _size->width, _size->height, 0, GL_RGB, GL_UNSIGNED_BYTE, image->data()[0]);
-	check_gl_error ("glTexImage2D");
+	if (_have_storage) {
+		glTexSubImage2D (GL_TEXTURE_2D, 0, 0, 0, _size->width, _size->height, GL_RGB, GL_UNSIGNED_BYTE, image->data()[0]);
+		check_gl_error ("glTexSubImage2D");
+	} else {
+		glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB8, _size->width, _size->height, 0, GL_RGB, GL_UNSIGNED_BYTE, image->data()[0]);
+		_have_storage = true;
+		check_gl_error ("glTexImage2D");
+	}
 
 	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
diff --git a/src/wx/gl_video_view.h b/src/wx/gl_video_view.h
index 827b12861..2f3c8c2a1 100644
--- a/src/wx/gl_video_view.h
+++ b/src/wx/gl_video_view.h
@@ -66,6 +66,7 @@ private:
 
 	GLuint _id;
 	boost::optional<dcp::Size> _size;
+	bool _have_storage;
 	bool _vsync_enabled;
 	boost::thread* _thread;