cogl: Stop using glPointSize in big-GL

Just pass it in to the vertex shader like in GLES, it's one less thing
to vary between drivers. mutter is, shall we say, not a heavy user of
point primitives, so any performance impact (it might be measurable, who
knows) is not an issue. Again, the feature flag remains to be cleaned up
in a future commit.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/995

cogl/cogl/cogl-pipeline.c

@@ -2799,14 +2799,7 @@ _cogl_pipeline_get_state_for_vertex_codegen (CoglContext *context)
                              COGL_PIPELINE_STATE_USER_SHADER |
                              COGL_PIPELINE_STATE_PER_VERTEX_POINT_SIZE |
                              COGL_PIPELINE_STATE_VERTEX_SNIPPETS);
-
+  state |= COGL_PIPELINE_STATE_NON_ZERO_POINT_SIZE;
-  /* If we don't have the builtin point size uniform then we'll add
-   * one in the GLSL but we'll only do this if the point size is
-   * non-zero. Whether or not the point size is zero is represented by
-   * COGL_PIPELINE_STATE_NON_ZERO_POINT_SIZE */
-  if (!_cogl_has_private_feature
-      (context, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM))
-    state |= COGL_PIPELINE_STATE_NON_ZERO_POINT_SIZE;
 
   return state;
 }

cogl/cogl/cogl-private.h

@@ -63,7 +63,6 @@ typedef enum
    * events. Otherwise a dirty event will be queued when the onscreen
    * is first allocated or when it is shown or resized */
   COGL_PRIVATE_FEATURE_DIRTY_EVENTS,
-  COGL_PRIVATE_FEATURE_ENABLE_PROGRAM_POINT_SIZE,
   /* This feature allows for explicitly selecting a GL-based backend,
    * as opposed to nop or (in the future) Vulkan.
    */

cogl/cogl/driver/gl/cogl-pipeline-opengl.c

@@ -64,9 +64,6 @@
 #ifndef GL_CLAMP_TO_BORDER
 #define GL_CLAMP_TO_BORDER 0x812d
 #endif
-#ifndef GL_PROGRAM_POINT_SIZE
-#define GL_PROGRAM_POINT_SIZE 0x8642
-#endif
 
 static void
 texture_unit_init (CoglContext *ctx,
@@ -456,21 +453,6 @@ _cogl_pipeline_flush_color_blend_alpha_depth_state (
         }
     }
 
-#ifdef HAVE_COGL_GL
-  if (_cogl_has_private_feature
-      (ctx, COGL_PRIVATE_FEATURE_ENABLE_PROGRAM_POINT_SIZE) &&
-      (pipelines_difference & COGL_PIPELINE_STATE_PER_VERTEX_POINT_SIZE))
-    {
-      unsigned long state = COGL_PIPELINE_STATE_PER_VERTEX_POINT_SIZE;
-      CoglPipeline *authority = _cogl_pipeline_get_authority (pipeline, state);
-
-      if (authority->big_state->per_vertex_point_size)
-        GE( ctx, glEnable (GL_PROGRAM_POINT_SIZE) );
-      else
-        GE( ctx, glDisable (GL_PROGRAM_POINT_SIZE) );
-    }
-#endif
-
   if (pipeline->real_blend_enable != ctx->gl_blend_enable_cache)
     {
       if (pipeline->real_blend_enable)

cogl/cogl/driver/gl/cogl-pipeline-vertend-glsl.c

@@ -305,8 +305,7 @@ _cogl_pipeline_vertend_glsl_start (CoglPipeline *pipeline,
   if (cogl_pipeline_get_per_vertex_point_size (pipeline))
     g_string_append (shader_state->header,
                      "attribute float cogl_point_size_in;\n");
-  else if (!_cogl_has_private_feature
+  else
-           (ctx, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM))
     {
       /* There is no builtin uniform for the point size on GLES2 so we
          need to copy it from the custom uniform in the vertex shader
@@ -541,19 +540,6 @@ _cogl_pipeline_vertend_glsl_end (CoglPipeline *pipeline,
       shader_state->gl_shader = shader;
     }
 
-#ifdef HAVE_COGL_GL
-  if (_cogl_has_private_feature
-      (ctx, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM) &&
-      (pipelines_difference & COGL_PIPELINE_STATE_POINT_SIZE))
-    {
-      CoglPipeline *authority =
-        _cogl_pipeline_get_authority (pipeline, COGL_PIPELINE_STATE_POINT_SIZE);
-
-      if (authority->big_state->point_size > 0.0f)
-        GE( ctx, glPointSize (authority->big_state->point_size) );
-    }
-#endif /* HAVE_COGL_GL */
-
   return TRUE;
 }
 
@@ -651,11 +637,7 @@ UNIT_TEST (check_point_size_shader,
    * size */
   if (shader_states[0])
     {
-      if (_cogl_has_private_feature
+      g_assert (shader_states[0] != shader_states[1]);
-          (test_ctx, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM))
-        g_assert (shader_states[0] == shader_states[1]);
-      else
-        g_assert (shader_states[0] != shader_states[1]);
     }
 
   /* The second and third pipelines should always have the same shader

cogl/cogl/driver/gl/gl/cogl-driver-gl.c

@@ -80,6 +80,11 @@ _cogl_driver_gl_context_init (CoglContext *context,
   if (context->driver == COGL_DRIVER_GL)
     GE (context, glEnable (GL_POINT_SPRITE));
 
+  /* There's no enable for this in GLES2, it's always on */
+  if (context->driver == COGL_DRIVER_GL ||
+      context->driver == COGL_DRIVER_GL3)
+    GE (context, glEnable (GL_PROGRAM_POINT_SIZE) );
+
   return TRUE;
 }
 
@@ -489,9 +494,6 @@ _cogl_driver_update_features (CoglContext *ctx,
     COGL_FLAGS_SET (private_features,
                     COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE, TRUE);
 
-  COGL_FLAGS_SET (private_features,
-                  COGL_PRIVATE_FEATURE_ENABLE_PROGRAM_POINT_SIZE, TRUE);
-
   if (ctx->driver == COGL_DRIVER_GL)
     {
       /* Features which are not available in GL 3 */
@@ -504,8 +506,6 @@ _cogl_driver_update_features (CoglContext *ctx,
   COGL_FLAGS_SET (private_features, COGL_PRIVATE_FEATURE_ANY_GL, TRUE);
   COGL_FLAGS_SET (private_features,
                   COGL_PRIVATE_FEATURE_FORMAT_CONVERSION, TRUE);
-  COGL_FLAGS_SET (private_features,
-                  COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM, TRUE);
   COGL_FLAGS_SET (private_features,
                   COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS, TRUE);
   COGL_FLAGS_SET (private_features,