mesa/st: Add depth clamping to rasterizer code

implemented by Erik Faye-Lund <[email protected]>

v2: Use current depth range values for clamping (Erik)
v3: fix scons-win64 build

Signed-off-by: Gert Wollny <[email protected]>
Reviewed-by: Reviewed-by: Marek Olšák <[email protected]>

2 files changed, 39 insertions, 6 deletions

diff --git a/src/mesa/state_tracker/st_atom_rasterizer.c b/src/mesa/state_tracker/st_atom_rasterizer.c
index 0d7d4c16fa6..b1ac4b3f133 100644
--- a/src/mesa/state_tracker/st_atom_rasterizer.c
+++ b/src/mesa/state_tracker/st_atom_rasterizer.c
@@ -295,8 +295,10 @@ st_update_rasterizer(struct st_context *st)
    }
 
    /* _NEW_TRANSFORM */
-   raster->depth_clip_near = !ctx->Transform.DepthClampNear;
-   raster->depth_clip_far = !ctx->Transform.DepthClampFar;
+   raster->depth_clip_near = st->clamp_frag_depth_in_shader ||
+                             !ctx->Transform.DepthClampNear;
+   raster->depth_clip_far = st->clamp_frag_depth_in_shader ||
+                            !ctx->Transform.DepthClampFar;
    raster->clip_plane_enable = ctx->Transform.ClipPlanesEnabled;
    raster->clip_halfz = (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE);
 
diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c b/src/mesa/state_tracker/st_cb_drawpixels.c
index ffbeae9fd7a..6c650fd1962 100644
--- a/src/mesa/state_tracker/st_cb_drawpixels.c
+++ b/src/mesa/state_tracker/st_cb_drawpixels.c
@@ -787,8 +787,10 @@ draw_textured_quad(struct gl_context *ctx, GLint x, GLint y, GLfloat z,
                                         ctx->Color._ClampFragmentColor;
       rasterizer.half_pixel_center = 1;
       rasterizer.bottom_edge_rule = 1;
-      rasterizer.depth_clip_near = !ctx->Transform.DepthClampNear;
-      rasterizer.depth_clip_far = !ctx->Transform.DepthClampFar;
+      rasterizer.depth_clip_near = st->clamp_frag_depth_in_shader ||
+                                   !ctx->Transform.DepthClampNear;
+      rasterizer.depth_clip_far = st->clamp_frag_depth_in_shader ||
+                                  !ctx->Transform.DepthClampFar;
       rasterizer.scissor = ctx->Scissor.EnableFlags;
       cso_set_rasterizer(cso, &rasterizer);
    }
@@ -1261,6 +1263,34 @@ setup_sampler_swizzle(struct pipe_sampler_view *sv, GLenum format, GLenum type)
 
 
 /**
+ * Compute the effective raster z position. This performs depth-clamping
+ * if needed.
+ */
+static float
+get_effective_raster_z(struct gl_context *ctx)
+{
+   float z = ctx->Current.RasterPos[2];
+   if (st_context(ctx)->clamp_frag_depth_in_shader) {
+      GLfloat depth_near;
+      GLfloat depth_far;
+      if (ctx->ViewportArray[0].Near < ctx->ViewportArray[0].Far) {
+         depth_near = ctx->ViewportArray[0].Near;
+         depth_far = ctx->ViewportArray[0].Far;
+      } else {
+         depth_near = ctx->ViewportArray[0].Far;
+         depth_far = ctx->ViewportArray[0].Near;
+      }
+
+      if (ctx->Transform.DepthClampNear)
+         z = MAX2(z, depth_near);
+      if (ctx->Transform.DepthClampFar)
+         z = MIN2(z, depth_far);
+   }
+   return z;
+}
+
+
+/**
  * Called via ctx->Driver.DrawPixels()
  */
 static void
@@ -1376,7 +1406,7 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
       num_sampler_view++;
    }
 
-   draw_textured_quad(ctx, x, y, ctx->Current.RasterPos[2],
+   draw_textured_quad(ctx, x, y, get_effective_raster_z(ctx),
                       width, height,
                       ctx->Pixel.ZoomX, ctx->Pixel.ZoomY,
                       sv,
@@ -1851,7 +1881,8 @@ st_CopyPixels(struct gl_context *ctx, GLint srcx, GLint srcy,
    /* OK, the texture 'pt' contains the src image/pixels.  Now draw a
     * textured quad with that texture.
     */
-   draw_textured_quad(ctx, dstx, dsty, ctx->Current.RasterPos[2],
+
+   draw_textured_quad(ctx, dstx, dsty, get_effective_raster_z(ctx),
                       width, height, ctx->Pixel.ZoomX, ctx->Pixel.ZoomY,
                       sv,
                       num_sampler_view,