From ee9db307520ff2bcb99d78f4f21be715cf2d5c22 Mon Sep 17 00:00:00 2001
From: Martin Pulec <martin.pulec@cesnet.cz>
Date: Mon, 9 May 2022 09:51:40 +0200
Subject: [PATCH] GL: change vsync back to 1

This reverts b80fcf18 while addressing the resize issue that the
original commit was supposed to solve.

Adaptive VSync may cause tearing if real frame rate is lower than
nominal (display) frame rate.

see also #227
---
 src/video_display/gl.cpp | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/src/video_display/gl.cpp b/src/video_display/gl.cpp
index bb9ae4090..d95a2f1c8 100644
--- a/src/video_display/gl.cpp
+++ b/src/video_display/gl.cpp
@@ -357,7 +357,7 @@ struct state_gl {
 
         time_ns_t       t0 = get_time_in_ns();
 
-        int             vsync = ADAPTIVE_VSYNC;
+        int             vsync = 1;
         bool            paused = false;
         enum show_cursor_t { SC_TRUE, SC_FALSE, SC_AUTOHIDE } show_cursor = SC_AUTOHIDE;
         chrono::steady_clock::time_point                      cursor_shown_from{}; ///< indicates time point from which is cursor show if show_cursor == SC_AUTOHIDE, timepoint() means cursor is not currently shown
@@ -1038,6 +1038,12 @@ static void gl_process_frames(struct state_gl *s)
                         return;
                 }
                 frame = s->frame_queue.front();
+
+                if (s->current_frame) {
+                        vf_recycle(s->current_frame);
+                        s->free_frame_queue.push(s->current_frame);
+                }
+                s->current_frame = frame;
         }
 
         if (!frame) {
@@ -1057,14 +1063,6 @@ static void gl_process_frames(struct state_gl *s)
                 gl_reconfigure_screen(s, video_desc_from_frame(frame));
         }
 
-        if (s->current_frame) {
-                s->lock.lock();
-                vf_recycle(s->current_frame);
-                s->free_frame_queue.push(s->current_frame);
-                s->lock.unlock();
-        }
-        s->current_frame = frame;
-
         gl_render(s, frame->tiles[0].data);
         gl_draw(s->aspect, (s->dxt_height - s->current_display_desc.height) / (float) s->dxt_height * 2, s->vsync != SINGLE_BUF);
 
@@ -1242,17 +1240,15 @@ static void display_gl_print_depth() {
 
 static void display_gl_render_last(GLFWwindow *win) {
         auto *s = (struct state_gl *) glfwGetWindowUserPointer(win);
-        if (!s->current_frame) {
+        unique_lock<mutex> lk(s->lock);
+        auto *f = s->current_frame;
+        s->current_frame = nullptr;
+        lk.unlock();
+        if (!f) {
                 return;
         }
         // redraw last frame
-        gl_render(s, s->current_frame->tiles[0].data);
-        gl_draw(s->aspect, (s->dxt_height - s->current_display_desc.height) / (float) s->dxt_height * 2, s->vsync != SINGLE_BUF);
-        if (s->vsync == SINGLE_BUF) {
-                glFlush();
-        } else {
-                glfwSwapBuffers(s->window);
-        }
+        display_gl_putf(s, f, PUTF_NONBLOCK);
 }
 
 #if defined HAVE_LINUX || defined WIN32