On 2 April 2017 at 22:43, Bas Nieuwenhuizen wrote:
> We want the guardband_x/y to be the largerst scalars such that each
> viewport scaled by that amount is still a subrange of [-32767, 32767].
>
> The old code has a couple of issues:
> 1) It used scissor instead of viewport_scissor, potentially taking into
>account a viewport that is too small and therefore selecting a scale
>that is too large.
> 2) Merging the viewports isn't ideal, as for example viewports with
>boundaries [0,1] and [1000, 1001] would allow a guardband scale of ~30k,
>while their union [0, 1001] only allows a scale of ~32.
>
> The new code just determines the guardband per viewport and takes the minimum.
>
> Signed-off-by: Bas Nieuwenhuizen
I'm not sure I understand guardband enough to say I know what this is doing,
Acked-by: Dave Airlie
> ---
> src/amd/vulkan/si_cmd_buffer.c | 52
> ++
> 1 file changed, 12 insertions(+), 40 deletions(-)
>
> diff --git a/src/amd/vulkan/si_cmd_buffer.c b/src/amd/vulkan/si_cmd_buffer.c
> index e176abe3869..bbcaf1009bd 100644
> --- a/src/amd/vulkan/si_cmd_buffer.c
> +++ b/src/amd/vulkan/si_cmd_buffer.c
> @@ -504,22 +504,6 @@ get_viewport_xform(const VkViewport *viewport,
> translate[2] = n;
> }
>
> -static void
> -get_viewport_xform_scissor(const VkRect2D *scissor,
> - float scale[2], float translate[2])
> -{
> - float x = scissor->offset.x;
> - float y = scissor->offset.y;
> - float half_width = 0.5f * scissor->extent.width;
> - float half_height = 0.5f * scissor->extent.height;
> -
> - scale[0] = half_width;
> - translate[0] = half_width + x;
> - scale[1] = half_height;
> - translate[1] = half_height + y;
> -
> -}
> -
> void
> si_write_viewport(struct radeon_winsys_cs *cs, int first_vp,
>int count, const VkViewport *viewports)
> @@ -579,26 +563,13 @@ static VkRect2D si_intersect_scissor(const VkRect2D *a,
> const VkRect2D *b) {
> return ret;
> }
>
> -static VkRect2D si_union_scissor(const VkRect2D *a, const VkRect2D *b) {
> - VkRect2D ret;
> - ret.offset.x = MIN2(a->offset.x, b->offset.x);
> - ret.offset.y = MIN2(a->offset.y, b->offset.y);
> - ret.extent.width = MAX2(a->offset.x + a->extent.width,
> - b->offset.x + b->extent.width) - ret.offset.x;
> - ret.extent.height = MAX2(a->offset.y + a->extent.height,
> -b->offset.y + b->extent.height) -
> ret.offset.y;
> - return ret;
> -}
> -
> -
> void
> si_write_scissors(struct radeon_winsys_cs *cs, int first,
>int count, const VkRect2D *scissors,
>const VkViewport *viewports, bool can_use_guardband)
> {
> int i;
> - VkRect2D merged;
> - float scale[2], translate[2], guardband_x = 1.0, guardband_y = 1.0;
> + float scale[3], translate[3], guardband_x = INFINITY, guardband_y =
> INFINITY;
> const float max_range = 32767.0f;
> assert(count);
>
> @@ -607,10 +578,14 @@ si_write_scissors(struct radeon_winsys_cs *cs, int
> first,
> VkRect2D viewport_scissor =
> si_scissor_from_viewport(viewports + i);
> VkRect2D scissor = si_intersect_scissor(&scissors[i],
> &viewport_scissor);
>
> - if (i)
> - merged = si_union_scissor(&merged, &scissor);
> - else
> - merged = scissor;
> + get_viewport_xform(viewports + i, scale, translate);
> + if (scale[0] < 0.5)
> + scale[0] = 0.5;
> + if (scale[1] < 0.5)
> + scale[1] = 0.5;
> +
> + guardband_x = MIN2(guardband_x, (max_range -
> abs(translate[0])) / scale[0]);
> + guardband_y = MIN2(guardband_y, (max_range -
> abs(translate[1])) / scale[1]);
>
> radeon_emit(cs, S_028250_TL_X(scissor.offset.x) |
> S_028250_TL_Y(scissor.offset.y) |
> @@ -618,12 +593,9 @@ si_write_scissors(struct radeon_winsys_cs *cs, int first,
> radeon_emit(cs, S_028254_BR_X(scissor.offset.x +
> scissor.extent.width) |
> S_028254_BR_Y(scissor.offset.y +
> scissor.extent.height));
> }
> -
> - get_viewport_xform_scissor(&merged, scale, translate);
> -
> - if (can_use_guardband) {
> - guardband_x = (max_range - abs(translate[0])) / scale[0];
> - guardband_y = (max_range - abs(translate[1])) / scale[1];
> + if (!can_use_guardband) {
> + guardband_x = 1.0;
> + guardband_y = 1.0;
> }
>
> radeon_set_context_reg_seq(cs, R_028BE8_PA_CL_GB_VERT_CLIP_ADJ, 4);
> --
> 2.12.1
>
> ___
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