[PATCH 1/5] wined3d: Fix immediate draws when ARB_vertex_array_bgra is not supported.

[Matteo Bruni]

2016-07-20 10:13 GMT+02:00 Henri Verbeet <hverbeet at gmail.com>:
> On 20 July 2016 at 00:33, Matteo Bruni <mbruni at codeweavers.com> wrote:
>> @@ -5848,7 +5850,7 @@ static void wined3d_adapter_init_ffp_attrib_ops(struct wined3d_adapter *adapter)
>>      ops->generic[WINED3D_FFP_EMIT_FLOAT2]     = (wined3d_generic_attrib_func)gl_info->gl_ops.ext.p_glVertexAttrib2fv;
>>      ops->generic[WINED3D_FFP_EMIT_FLOAT3]     = (wined3d_generic_attrib_func)gl_info->gl_ops.ext.p_glVertexAttrib3fv;
>>      ops->generic[WINED3D_FFP_EMIT_FLOAT4]     = (wined3d_generic_attrib_func)gl_info->gl_ops.ext.p_glVertexAttrib4fv;
>> -    if (gl_info->supported[ARB_VERTEX_ARRAY_BGRA])
>> +    if (!gl_info->supported[ARB_VERTEX_ARRAY_BGRA])
>>          ops->generic[WINED3D_FFP_EMIT_D3DCOLOR] = generic_d3dcolor;
>>      else
>>          ops->generic[WINED3D_FFP_EMIT_D3DCOLOR] =
> This looks wrong. When ARB_vertex_array_bgra is not supported, shaders
> swizzle the corresponding input registers (see also
> shader_glsl_swizzle_to_str() and shader_arb_get_swizzle()), so the
> attribute upload code shouldn't.

It's a bit more convoluted than that. When ARB_vertex_array_bgra is
not supported, FFP draws usually fall back to immediate mode because
of the check in context_update_stream_info(). There is no shader
swizzling in that case so we need to swizzle when uploading the
attribute. If ARB_vertex_array_bgra is supported we never need to
swizzle the attribute so the above change seems at least a fix for
that case (although if ARB_vertex_array_bgra is supported we generally
don't fallback to immediate mode either, so that doesn't matter much
in practice).
context_update_stream_info() only checks for DIFFUSE and SPECULAR
though so I guess if other attributes use D3DCOLOR we're currently
screwed.

The immediate mode check is in the !VS-only branch so it would not
apply to non-FFP draws. Those get the shader swizzle instead and thus
work fine. I guess there is an exception here too which is instanced
draws when both ARB_vertex_array_bgra and ARB_instanced_arrays are
missing AND one of the instance attributes is D3DCOLOR.

Eventually for GL ES (which I think doesn't have anything equivalent
to ARB_vertex_array_bgra) we'll need to always handle this in the
shader since we can't fallback to immediate mode there. I guess I'll
try to write a patch going in that direction since it should also
clean things up WRT the above cases on desktop OpenGL.