nVidia's GLSL compiler spits out a warning if a value is potentially used without being initialized. This affects many of wined3d's GLSL shaders, as either some element of the (e.g.) vs_out array are not initialized, or individual vector components remain unwritten to.
As a quick way of working around this, initialize all vs_out, gs_out, and temporary Rn registers to vec4(0,0,0,0). This gets rid of all of the warnings in the cases I tried.
(A more complete solution would probably track if we're initialising these, and only add what is required. Or would just disable the warning somehow.)
Some example warnings (from a shader in the 'Pharaoh: A New Era' demo): ``` 0264:fixme:d3d_shader:print_glsl_info_log Info log received from GLSL shader #3: 0264:fixme:d3d_shader:print_glsl_info_log Vertex info 0264:fixme:d3d_shader:print_glsl_info_log ----------- 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[2].zw" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[5].w" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[7]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[8]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[9]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[10]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[11]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[12]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[13]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[14]" might be used before being initialized 0264:fixme:d3d_shader:print_glsl_info_log 0(28) : warning C7050: "vs_out[15]" might be used before being initialized ```