vkd3d-shader: Introduce an interface to specify sm1 shadow samplers.

Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/1769

include/vkd3d_shader.h

@@ -2350,6 +2350,26 @@ struct vkd3d_shader_d3dbc_source_info
      * This field is ignored for shader models 2 and higher.
      */
     enum vkd3d_shader_resource_type texture_dimensions[6];
+
+    /**
+     * A mask indicating which samplers should be shadow (i.e. comparison-mode)
+     * samplers. When legacy Direct3D shaders are used with the Direct3D 8 and 9
+     * APIs, this is implied by the format of the sampled resource; e.g. a
+     * D3DFMT_D24S8 texture implies shadow sampling, while a D3DFMT_A8R8G8B8
+     * or D3DFMT_INTZ texture does not.
+     * This information is necessary when converting to other formats
+     * (e.g. SPIR-V, GLSL) which specify this in the shader.
+     *
+     * For example, if bit 1 is set (so the value is 0x2), this indicates that
+     * the sampler at bind point 1 (and no others) should be a shadow sampler.
+     *
+     * Bits in this mask corresponding to textures not used by the shader will
+     * be ignored.
+     *
+     * If this structure is not specified, no samplers will be considered to
+     * be shadow samplers.
+     */
+    uint32_t shadow_samplers;
 };
 
 /**