=?UTF-8?Q?J=C3=B3zef=20Kucia=20?=: wined3d: Disable transform feedback when there are no varyings to record.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: f6160d2ae80d6dd53ce74b53fe006163ee3e720a
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=f6160d2ae80d6dd53ce74b53fe006163ee3e720a

Author: Józef Kucia <jkucia at codeweavers.com>
Date:   Thu Apr 26 14:53:24 2018 +0200

wined3d: Disable transform feedback when there are no varyings to record.

In order to avoid GL errors when glBeginTransformFeedback() is called.
This is required only because we do not fully support stream output
component ranges.

Signed-off-by: Józef Kucia <jkucia at codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/wined3d/glsl_shader.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/dlls/wined3d/glsl_shader.c b/dlls/wined3d/glsl_shader.c
index e29730c..5d1f118 100644
--- a/dlls/wined3d/glsl_shader.c
+++ b/dlls/wined3d/glsl_shader.c
@@ -804,11 +804,12 @@ static void append_transform_feedback_skip_components(const char **varyings,
     }
 }
 
-static void shader_glsl_generate_transform_feedback_varyings(const struct wined3d_stream_output_desc *so_desc,
+static BOOL shader_glsl_generate_transform_feedback_varyings(const struct wined3d_stream_output_desc *so_desc,
         struct wined3d_string_buffer *buffer, const char **varyings, unsigned int *varying_count,
         char *strings, unsigned int *strings_length, GLenum buffer_mode)
 {
     unsigned int i, buffer_idx, count, length, highest_output_slot, stride;
+    BOOL have_varyings_to_record = FALSE;
 
     count = length = 0;
     highest_output_slot = 0;
@@ -858,6 +859,8 @@ static void shader_glsl_generate_transform_feedback_varyings(const struct wined3
                 string_buffer_sprintf(buffer, "shader_in_out.reg%u", e->register_idx);
                 append_transform_feedback_varying(varyings, &count, &strings, &length, buffer);
             }
+
+            have_varyings_to_record = TRUE;
         }
 
         if (buffer_idx < so_desc->buffer_stride_count
@@ -882,10 +885,12 @@ static void shader_glsl_generate_transform_feedback_varyings(const struct wined3
         *varying_count = count;
     if (strings_length)
         *strings_length = length;
+
+    return have_varyings_to_record;
 }
 
 static void shader_glsl_init_transform_feedback(const struct wined3d_context *context,
-        struct shader_glsl_priv *priv, GLuint program_id, const struct wined3d_shader *shader)
+        struct shader_glsl_priv *priv, GLuint program_id, struct wined3d_shader *shader)
 {
     const struct wined3d_stream_output_desc *so_desc = &shader->u.gs.so_desc;
     const struct wined3d_gl_info *gl_info = context->gl_info;
@@ -941,7 +946,12 @@ static void shader_glsl_init_transform_feedback(const struct wined3d_context *co
 
     buffer = string_buffer_get(&priv->string_buffers);
 
-    shader_glsl_generate_transform_feedback_varyings(so_desc, buffer, NULL, &count, NULL, &length, mode);
+    if (!shader_glsl_generate_transform_feedback_varyings(so_desc, buffer, NULL, &count, NULL, &length, mode))
+    {
+        FIXME("No varyings to record, disabling transform feedback.\n");
+        shader->u.gs.so_desc.element_count = 0;
+        return;
+    }
 
     if (!(varyings = heap_calloc(count, sizeof(*varyings))))
     {