From bf9a1e0a4be96b5f74d792596b10394ca9092703 Mon Sep 17 00:00:00 2001
From: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Date: Fri, 16 Oct 2020 12:18:59 -0400
Subject: [PATCH] zink: add a pipe_context::get_sample_position hook

standard for most gallium drivers, not sure why it's not a util function

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7192>
---
 src/gallium/drivers/zink/zink_context.c | 73 +++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/src/gallium/drivers/zink/zink_context.c b/src/gallium/drivers/zink/zink_context.c
index 46545b741d7..f223c8366b6 100644
--- a/src/gallium/drivers/zink/zink_context.c
+++ b/src/gallium/drivers/zink/zink_context.c
@@ -310,6 +310,78 @@ zink_sampler_view_destroy(struct pipe_context *pctx,
    FREE(view);
 }
 
+static void
+zink_get_sample_position(struct pipe_context *ctx,
+                         unsigned sample_count,
+                         unsigned sample_index,
+                         float *out_value)
+{
+   /* TODO: handle this I guess */
+   assert(zink_screen(ctx->screen)->info.props.limits.standardSampleLocations);
+   /* from 26.4. Multisampling */
+   switch (sample_count) {
+   case 0:
+   case 1: {
+      float pos[][2] = { {0.5,0.5}, };
+      out_value[0] = pos[sample_index][0];
+      out_value[1] = pos[sample_index][1];
+      break;
+   }
+   case 2: {
+      float pos[][2] = { {0.75,0.75},
+                        {0.25,0.25}, };
+      out_value[0] = pos[sample_index][0];
+      out_value[1] = pos[sample_index][1];
+      break;
+   }
+   case 4: {
+      float pos[][2] = { {0.375, 0.125},
+                        {0.875, 0.375},
+                        {0.125, 0.625},
+                        {0.625, 0.875}, };
+      out_value[0] = pos[sample_index][0];
+      out_value[1] = pos[sample_index][1];
+      break;
+   }
+   case 8: {
+      float pos[][2] = { {0.5625, 0.3125},
+                        {0.4375, 0.6875},
+                        {0.8125, 0.5625},
+                        {0.3125, 0.1875},
+                        {0.1875, 0.8125},
+                        {0.0625, 0.4375},
+                        {0.6875, 0.9375},
+                        {0.9375, 0.0625}, };
+      out_value[0] = pos[sample_index][0];
+      out_value[1] = pos[sample_index][1];
+      break;
+   }
+   case 16: {
+      float pos[][2] = { {0.5625, 0.5625},
+                        {0.4375, 0.3125},
+                        {0.3125, 0.625},
+                        {0.75, 0.4375},
+                        {0.1875, 0.375},
+                        {0.625, 0.8125},
+                        {0.8125, 0.6875},
+                        {0.6875, 0.1875},
+                        {0.375, 0.875},
+                        {0.5, 0.0625},
+                        {0.25, 0.125},
+                        {0.125, 0.75},
+                        {0.0, 0.5},
+                        {0.9375, 0.25},
+                        {0.875, 0.9375},
+                        {0.0625, 0.0}, };
+      out_value[0] = pos[sample_index][0];
+      out_value[1] = pos[sample_index][1];
+      break;
+   }
+   default:
+      unreachable("unhandled sample count!");
+   }
+}
+
 static void
 zink_set_polygon_stipple(struct pipe_context *pctx,
                          const struct pipe_poly_stipple *ps)
@@ -1104,6 +1176,7 @@ zink_context_create(struct pipe_screen *pscreen, void *priv, unsigned flags)
    ctx->base.create_sampler_view = zink_create_sampler_view;
    ctx->base.set_sampler_views = zink_set_sampler_views;
    ctx->base.sampler_view_destroy = zink_sampler_view_destroy;
+   ctx->base.get_sample_position = zink_get_sample_position;
 
    zink_program_init(ctx);