wined3d: Implement SV_IsFrontFace input sysval semantic.

dlls/wined3d/glsl_shader.c

@@ -5310,6 +5310,10 @@ static void shader_glsl_input_pack(const struct wined3d_shader *shader, struct w
                         shader->u.ps.input_reg_map[input->register_idx], reg_mask, reg_mask);
             else if (args->pointsprite && shader_match_semantic(semantic_name, WINED3D_DECL_USAGE_TEXCOORD))
                 shader_addline(buffer, "ps_in[%u] = vec4(gl_PointCoord.xy, 0.0, 0.0);\n", input->register_idx);
+            else if (input->sysval_semantic == WINED3D_SV_IS_FRONT_FACE)
+                shader_addline(buffer, "ps_in[%u] = vec4("
+                        "uintBitsToFloat(gl_FrontFacing ? 0xffffffffu : 0u), 0.0, 0.0, 0.0);\n",
+                        input->register_idx);
             else
                 shader_addline(buffer, "ps_in[%u]%s = ps_link[%u]%s;\n",
                         shader->u.ps.input_reg_map[input->register_idx], reg_mask,

dlls/wined3d/shader.c

@@ -1311,9 +1311,13 @@ static HRESULT shader_get_registers_used(struct wined3d_shader *shader, const st
         for (i = 0; i < input_signature->element_count; ++i)
         {
             reg_maps->input_registers |= 1u << input_signature->elements[i].register_idx;
-            if (shader_version.type == WINED3D_SHADER_TYPE_PIXEL
-                    && input_signature->elements[i].sysval_semantic == WINED3D_SV_POSITION)
-                reg_maps->vpos = 1;
+            if (shader_version.type == WINED3D_SHADER_TYPE_PIXEL)
+            {
+                if (input_signature->elements[i].sysval_semantic == WINED3D_SV_POSITION)
+                    reg_maps->vpos = 1;
+                else if (input_signature->elements[i].sysval_semantic == WINED3D_SV_IS_FRONT_FACE)
+                    reg_maps->usesfacing = 1;
+            }
         }
     }
     else if (!input_signature->elements && reg_maps->input_registers)