[Mesa-dev] [PATCH 4/4] anv: Clamp scissors to the framebuffer boundary

[Jason Ekstrand]

The Vulkan 1.1.81 spec says:

    "It is legal for offset.x + extent.width or offset.y + extent.height
    to exceed the dimensions of the framebuffer - the scissor test still
    applies as defined above. Rasterization does not produce fragments
    outside of the framebuffer, so such fragments never have the scissor
    test performed on them."

For the past two years, I've been misreading this as saying that having
a too-large scissor is ILLEGAL which is clearly not what it says.  Since
we set drawing rectangle once at context initialization time, we can't
trust in that to catch us and we need to fix up the scissor.
Fortunately, the user is required to provide us with at least one
scissor so we don't need to handle the case where they don't.

Fixes: fb2a5ceb3264 "anv: Emit DRAWING_RECTANGLE once at driver..."
---
 src/intel/vulkan/gen7_cmd_buffer.c | 5 +++--
 src/intel/vulkan/genX_cmd_buffer.c | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/intel/vulkan/gen7_cmd_buffer.c b/src/intel/vulkan/gen7_cmd_buffer.c
index 3acfbb710c0..cf1f8ee2829 100644
--- a/src/intel/vulkan/gen7_cmd_buffer.c
+++ b/src/intel/vulkan/gen7_cmd_buffer.c
@@ -48,6 +48,7 @@ clamp_int64(int64_t x, int64_t min, int64_t max)
 void
 gen7_cmd_buffer_emit_scissor(struct anv_cmd_buffer *cmd_buffer)
 {
+   struct anv_framebuffer *fb = cmd_buffer->state.framebuffer;
    uint32_t count = cmd_buffer->state.gfx.dynamic.scissor.count;
    const VkRect2D *scissors = cmd_buffer->state.gfx.dynamic.scissor.scissors;
    struct anv_state scissor_state =
@@ -73,8 +74,8 @@ gen7_cmd_buffer_emit_scissor(struct anv_cmd_buffer *cmd_buffer)
          /* Do this math using int64_t so overflow gets clamped correctly. */
          .ScissorRectangleYMin = clamp_int64(s->offset.y, 0, max),
          .ScissorRectangleXMin = clamp_int64(s->offset.x, 0, max),
-         .ScissorRectangleYMax = clamp_int64((uint64_t) s->offset.y + s->extent.height - 1, 0, max),
-         .ScissorRectangleXMax = clamp_int64((uint64_t) s->offset.x + s->extent.width - 1, 0, max)
+         .ScissorRectangleYMax = clamp_int64((uint64_t) s->offset.y + s->extent.height - 1, 0, fb->height - 1),
+         .ScissorRectangleXMax = clamp_int64((uint64_t) s->offset.x + s->extent.width - 1, 0, fb->width - 1)
       };
 
       if (s->extent.width <= 0 || s->extent.height <= 0) {
diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
index 75b3dd54275..7221a2d4328 100644
--- a/src/intel/vulkan/genX_cmd_buffer.c
+++ b/src/intel/vulkan/genX_cmd_buffer.c
@@ -2623,7 +2623,8 @@ genX(cmd_buffer_flush_state)(struct anv_cmd_buffer *cmd_buffer)
                                           pipeline->depth_clamp_enable);
    }
 
-   if (cmd_buffer->state.gfx.dirty & ANV_CMD_DIRTY_DYNAMIC_SCISSOR)
+   if (cmd_buffer->state.gfx.dirty & (ANV_CMD_DIRTY_DYNAMIC_SCISSOR |
+                                      ANV_CMD_DIRTY_RENDER_TARGETS))
       gen7_cmd_buffer_emit_scissor(cmd_buffer);
 
    genX(cmd_buffer_flush_dynamic_state)(cmd_buffer);
-- 
2.17.1