vo_opengl: test FBOs only if they're going to be used

Change test_fbo() so that it checks the FBO lazily, and restructure
check_gl_features() to invoke it only if we know that a FBO will be
needed for a certain enabled feature.

This can avoid strange error messages when using --vo=opengl and the
FBO format does not work. It's also less confusing when reading the
verbose log (users might think that the FBO is actually used, etc.).

(cherry picked from commit 280c826379dfdebb9e949d22583c01d532a504c7)

1 files changed, 28 insertions, 30 deletions

diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index d5e5957e38..ee1817ae69 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -2086,20 +2086,26 @@ void gl_video_upload_image(struct gl_video *p, struct mp_image *mpi)
         gl->BindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
 }
 
-static bool test_fbo(struct gl_video *p, GLenum format)
+static bool test_fbo(struct gl_video *p, bool *success)
 {
+    if (!*success)
+        return false;
+
     GL *gl = p->gl;
-    bool success = false;
+    *success = false;
+    MP_VERBOSE(p, "Testing user-set FBO format (0x%x)\n",
+                   (unsigned)p->opts.fbo_format);
     struct fbotex fbo = {0};
-    if (fbotex_init(&fbo, p->gl, p->log, 16, 16, p->gl_target, GL_LINEAR, format))
+    if (fbotex_init(&fbo, p->gl, p->log, 16, 16, p->gl_target, GL_LINEAR,
+                    p->opts.fbo_format))
     {
         gl->BindFramebuffer(GL_FRAMEBUFFER, fbo.fbo);
         gl->BindFramebuffer(GL_FRAMEBUFFER, 0);
-        success = true;
+        *success = true;
     }
     fbotex_uninit(&fbo);
     glCheckError(gl, p->log, "FBO test");
-    return success;
+    return *success;
 }
 
 // Disable features that are not supported with the current OpenGL version.
@@ -2116,33 +2122,25 @@ static void check_gl_features(struct gl_video *p)
     char *disabled[10];
     int n_disabled = 0;
 
-    if (have_fbo) {
-        MP_VERBOSE(p, "Testing user-set FBO format (0x%x)\n",
-                   (unsigned)p->opts.fbo_format);
-        have_fbo = test_fbo(p, p->opts.fbo_format);
-    }
-
     // Normally, we want to disable them by default if FBOs are unavailable,
     // because they will be slow (not critically slow, but still slower).
     // Without FP textures, we must always disable them.
     // I don't know if luminance alpha float textures exist, so disregard them.
-    if (!have_float_tex || !have_arrays || !have_fbo || !have_1d_tex) {
-        for (int n = 0; n < 2; n++) {
-            const struct filter_kernel *kernel = mp_find_filter_kernel(p->opts.scalers[n]);
-            if (kernel) {
-                char *reason = "";
-                if (!have_fbo)
-                    reason = "scaler (FBO)";
-                if (!have_float_tex)
-                    reason = "scaler (float tex.)";
-                if (!have_arrays)
-                    reason = "scaler (no GLSL support)";
-                if (!have_1d_tex && kernel->polar)
-                    reason = "scaler (1D tex.)";
-                if (*reason) {
-                    p->opts.scalers[n] = "bilinear";
-                    disabled[n_disabled++] = reason;
-                }
+    for (int n = 0; n < 2; n++) {
+        const struct filter_kernel *kernel = mp_find_filter_kernel(p->opts.scalers[n]);
+        if (kernel) {
+            char *reason = NULL;
+            if (!test_fbo(p, &have_fbo))
+                reason = "scaler (FBO)";
+            if (!have_float_tex)
+                reason = "scaler (float tex.)";
+            if (!have_arrays)
+                reason = "scaler (no GLSL support)";
+            if (!have_1d_tex && kernel->polar)
+                reason = "scaler (1D tex.)";
+            if (reason) {
+                p->opts.scalers[n] = "bilinear";
+                disabled[n_disabled++] = reason;
             }
         }
     }
@@ -2167,12 +2165,12 @@ static void check_gl_features(struct gl_video *p)
         p->opts.srgb = false;
         disabled[n_disabled++] = "sRGB output (GLSL version)";
     }
-    if (!have_fbo && use_cms) {
+    if (use_cms && !test_fbo(p, &have_fbo)) {
         p->opts.srgb = false;
         p->use_lut_3d = false;
         disabled[n_disabled++] = "color management (FBO)";
     }
-    if (!have_fbo && p->opts.smoothmotion) {
+    if (p->opts.smoothmotion && !test_fbo(p, &have_fbo)) {
         p->opts.smoothmotion = false;
         disabled[n_disabled++] = "smoothmotion (FBO)";
     }