wined3d: Pass a correct access flag to glMapBufferARB.

dlls/wined3d/resource.c

@@ -419,3 +419,12 @@ GLbitfield wined3d_resource_gl_map_flags(DWORD d3d_flags)
 
     return ret;
 }
+
+GLenum wined3d_resource_gl_legacy_map_flags(DWORD d3d_flags)
+{
+    if (d3d_flags & WINED3D_MAP_READONLY)
+        return GL_READ_ONLY_ARB;
+    if (d3d_flags & (WINED3D_MAP_DISCARD | WINED3D_MAP_NOOVERWRITE))
+        return GL_WRITE_ONLY_ARB;
+    return GL_READ_WRITE_ARB;
+}

dlls/wined3d/volume.c

@@ -642,7 +642,8 @@ HRESULT CDECL wined3d_volume_map(struct wined3d_volume *volume,
         }
         else
         {
-            base_memory = GL_EXTCALL(glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, 0));
+            GLenum access = wined3d_resource_gl_legacy_map_flags(flags);
+            base_memory = GL_EXTCALL(glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, access));
         }
 
         GL_EXTCALL(glBindBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, 0));

dlls/wined3d/wined3d_private.h

@@ -2025,6 +2025,7 @@ void wined3d_resource_free_sysmem(struct wined3d_resource *resource) DECLSPEC_HI
 DWORD wined3d_resource_sanitize_map_flags(const struct wined3d_resource *resource,
         DWORD flags) DECLSPEC_HIDDEN;
 GLbitfield wined3d_resource_gl_map_flags(DWORD d3d_flags) DECLSPEC_HIDDEN;
+GLenum wined3d_resource_gl_legacy_map_flags(DWORD d3d_flags) DECLSPEC_HIDDEN;
 
 /* Tests show that the start address of resources is 32 byte aligned */
 #define RESOURCE_ALIGNMENT 16