On Wed, Nov 02, 2011 at 02:18:46PM -0700, Eric Anholt wrote: > On Wed, 2 Nov 2011 11:12:07 +0800, Yuanhan Liu <[email protected]> > wrote: > > On Tue, Nov 01, 2011 at 05:57:36PM +0800, Yuanhan Liu wrote: > > > According to bspec, MIPCnt(was set to intelObj->_MaxLevel) was used for > > > min/mag filter mode determination. For a normal case with no mipmap like > > > this: > > > > > > glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); > > > glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); > > > > > > hardware would always choose mag filter(GL_LINEAR) here since MIPCnt was > > > set to 0 zero, then would make LOD be zero. Then according the formula: > > > MagMode = (LOD - Base <= 0) > > > > Here are some more comments about this: LOD is a pre-computed value. if > > preClamp is enabled, then LOD would be: > > LOD = min(min(MIPCnt, MAX_LOD), LOD); > > > > So, if MIPCnt was set to 0, and preClamp was enabled, then the _final_ > > LOD would be 0, and hardware choose mag filter. > > > > Thoughts? > > It took me a long time to understand what you were trying to fix here.
Sorry for that :( > The story I've worked out is: > > "We can't optimize out uploading the other mipmap levels for > non-mipmapped filtering modes if the min filter is not the same as the > mag filter. This is because the min/mag decision is based on the > computed LOD of the sample, and if we clamp the LOD to BaseLevel by not > including the other levels, it will always choose the mag filter even if > minification should have occurred. Yes. > See page FINISHME: citation of PRM." Sorry, what does this mean? > > Particularly what was unclear was that the patch was just skipping an > optimization, to get behavior back in line with what the user did through > the API: Specify multiple levels in their texture. Yeah, I saw that. While thinking about this issue, I thought another patch to fix this issue. It's somehow against with the Bspec: preclamp should be enabled for OpenGL driver. Anyway, here is the patch, and I'd like to know what's your thoughts. --- >From 052b646f5db1da338244325750fb50d28f77d575 Mon Sep 17 00:00:00 2001 From: Yuanhan Liu <[email protected]> Date: Thu, 3 Nov 2011 10:01:25 +0800 Subject: [PATCH] i965: make sure hardware choose the right filter mode Here I quoted Eric's words: the min/mag decision is based on the computed LOD of the sample, and if we clamp the LOD to BaseLevel by not including the other levels, it will always choose the mag filter even if minification should have occurred And here is how the hardware do the min/mag decision in a formula way: MagMode = (LOD - Base <= 0) where LOD is computed in a way like the following if preClamp is enabled: if (preClamp is enabled) LOD = min(min(MIPCnt, MAX_LOD), pre-computed_LOD); else LOD = per-computed_LOD; So, if have just one level(the baselevel), just don't enable preclamp to make hardware choose the right filter mode. This would fix all oglc filtercubemin subcase fail and introduce no oglc regression. Signed-off-by: Yuanhan Liu <[email protected]> --- src/mesa/drivers/dri/i965/brw_wm_sampler_state.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c index 6104afc..f102573 100644 --- a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c +++ b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c @@ -164,8 +164,10 @@ static void brw_update_sampler_state(struct brw_context *brw, struct gl_context *ctx = &intel->ctx; struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit]; struct gl_texture_object *texObj = texUnit->_Current; + struct intel_texture_object *intelObj = intel_texture_object(texObj); struct gl_sampler_object *gl_sampler = _mesa_get_samplerobj(ctx, unit); bool using_nearest = false; + int mip_cnt = intelObj->_MaxLevel - texObj->BaseLevel; switch (gl_sampler->MinFilter) { case GL_NEAREST: @@ -275,6 +277,13 @@ static void brw_update_sampler_state(struct brw_context *brw, gl_sampler->LodBias, -16, 15), 6); sampler->ss0.lod_preclamp = 1; /* OpenGL mode */ + /* + * Workaround: if mip count is set to 0 and preclamp is enabled, + * this would clamp * the final lod to 0 and then hardware would + * always choose mag filter. + */ + if (gl_sampler->MinFilter != gl_sampler->MagFilter && mip_cnt == 0) + sampler->ss0.lod_preclamp = 0; sampler->ss0.default_color_mode = 0; /* OpenGL/DX10 mode */ /* Set BaseMipLevel, MaxLOD, MinLOD: -- 1.7.4.4 _______________________________________________ mesa-dev mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-dev
