From 17c877659c2e2366a94fd7600ffd4084ab52f67d Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Fri, 17 Mar 2023 06:26:05 +0100
Subject: [PATCH] glrenderer: Support GL without samplers

We cheat and just set the texture parameters instead and hope nothing
explodes.
So far it didn't.

This is only needed to support GLES 2.0 so it's quite a limited set of
hardware these days.
---
 gsk/gl/gskglcommandqueue.c        | 33 +++++++++++++++++++++++--------
 gsk/gl/gskglcommandqueueprivate.h |  3 +++
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/gsk/gl/gskglcommandqueue.c b/gsk/gl/gskglcommandqueue.c
index 4352ec29da..c0cee895d4 100644
--- a/gsk/gl/gskglcommandqueue.c
+++ b/gsk/gl/gskglcommandqueue.c
@@ -411,7 +411,8 @@ gsk_gl_command_queue_dispose (GObject *object)
   g_clear_pointer (&self->attachments, gsk_gl_attachment_state_unref);
   g_clear_pointer (&self->uniforms, gsk_gl_uniform_state_unref);
 
-  glDeleteSamplers (G_N_ELEMENTS (self->samplers), self->samplers);
+  if (self->has_samplers)
+    glDeleteSamplers (G_N_ELEMENTS (self->samplers), self->samplers);
 
   gsk_gl_command_batches_clear (&self->batches);
   gsk_gl_command_binds_clear (&self->batch_binds);
@@ -480,14 +481,19 @@ gsk_gl_command_queue_new (GdkGLContext      *context,
         }
     }
 
+  self->has_samplers = gdk_gl_context_check_version (context, 3, 3, 3, 0);
+
   /* create the samplers */
-  glGenSamplers (G_N_ELEMENTS (self->samplers), self->samplers);
-  for (i = 0; i < G_N_ELEMENTS (self->samplers); i++)
+  if (self->has_samplers)
     {
-      glSamplerParameteri (self->samplers[i], GL_TEXTURE_MIN_FILTER, filter_from_index(i / GSK_GL_N_FILTERS));
-      glSamplerParameteri (self->samplers[i], GL_TEXTURE_MAG_FILTER, filter_from_index(i % GSK_GL_N_FILTERS));
-      glSamplerParameteri (self->samplers[i], GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-      glSamplerParameteri (self->samplers[i], GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+      glGenSamplers (G_N_ELEMENTS (self->samplers), self->samplers);
+      for (i = 0; i < G_N_ELEMENTS (self->samplers); i++)
+        {
+          glSamplerParameteri (self->samplers[i], GL_TEXTURE_MIN_FILTER, filter_from_index(i / GSK_GL_N_FILTERS));
+          glSamplerParameteri (self->samplers[i], GL_TEXTURE_MAG_FILTER, filter_from_index(i % GSK_GL_N_FILTERS));
+          glSamplerParameteri (self->samplers[i], GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+          glSamplerParameteri (self->samplers[i], GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        }
     }
 
   return g_steal_pointer (&self);
@@ -1153,11 +1159,22 @@ gsk_gl_command_queue_execute (GskGLCommandQueue    *self,
 
                       glBindTexture (GL_TEXTURE_2D, bind->id);
                       textures[bind->texture] = bind->id;
+                      if (!self->has_samplers)
+                        {
+                          glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter_from_index(bind->sampler / GSK_GL_N_FILTERS));
+                          glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter_from_index(bind->sampler % GSK_GL_N_FILTERS));
+                        }
                     }
 
                   if (samplers[bind->texture] != bind->sampler)
                     {
-                      glBindSampler (bind->texture, self->samplers[bind->sampler]);
+                      if (self->has_samplers)
+                        glBindSampler (bind->texture, self->samplers[bind->sampler]);
+                      else
+                        {
+                          glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter_from_index(bind->sampler / GSK_GL_N_FILTERS));
+                          glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter_from_index(bind->sampler % GSK_GL_N_FILTERS));
+                        }
                       samplers[bind->texture] = bind->sampler;
                     }
 
diff --git a/gsk/gl/gskglcommandqueueprivate.h b/gsk/gl/gskglcommandqueueprivate.h
index d10d25a661..388745ea6f 100644
--- a/gsk/gl/gskglcommandqueueprivate.h
+++ b/gsk/gl/gskglcommandqueueprivate.h
@@ -266,6 +266,9 @@ struct _GskGLCommandQueue
   /* Counter for uploads on the frame */
   guint n_uploads;
 
+  /* If the GL context is new enough for sampler support */
+  guint has_samplers : 1;
+
   /* If we're inside a begin/end_frame pair */
   guint in_frame : 1;