mesa: Clamp some depth values in glClearBufferfi
OpenGL 3.0 spec, section 4.2.3 "Clearing the Buffers":
depth and stencil are the values to clear the depth and stencil
buffers to, respectively. Clamping and type conversion for
fixed-point depth buffers are performed in the same fashion as for
ClearDepth.
Enables iris to pass the clearbuffer-depth-stencil piglit test.
Cc: mesa-stable
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7410>
(cherry picked from commit 2e713313a29422b38435c91f8277c1893fcad095)
diff --git a/.pick_status.json b/.pick_status.json
index ad51376..2396e4e 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -1084,7 +1084,7 @@
"description": "mesa: Clamp some depth values in glClearBufferfi",
"nominated": true,
"nomination_type": 0,
- "resolution": 0,
+ "resolution": 1,
"master_sha": null,
"because_sha": null
},
diff --git a/src/mesa/main/clear.c b/src/mesa/main/clear.c
index 0a51a86..ba978a0 100644
--- a/src/mesa/main/clear.c
+++ b/src/mesa/main/clear.c
@@ -738,8 +738,20 @@
const GLclampd clearDepthSave = ctx->Depth.Clear;
const GLuint clearStencilSave = ctx->Stencil.Clear;
- /* set new clear values */
- ctx->Depth.Clear = depth;
+ /* set new clear values
+ *
+ * Page 263 (page 279 of the PDF) of the OpenGL 3.0 spec says:
+ *
+ * "depth and stencil are the values to clear the depth and stencil
+ * buffers to, respectively. Clamping and type conversion for
+ * fixed-point depth buffers are performed in the same fashion as
+ * for ClearDepth."
+ */
+ const struct gl_renderbuffer *rb =
+ ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
+ const bool has_float_depth = rb &&
+ _mesa_has_depth_float_channel(rb->InternalFormat);
+ ctx->Depth.Clear = has_float_depth ? depth : SATURATE(depth);
ctx->Stencil.Clear = stencil;
/* clear buffers */