v3dv: simplify scissor setup for negative viewport height

KHR_maintenance1 allows clients to specify a negative
height, but not a negative width, so assert on that and
simplify the computations for the horizontal dimension.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23489>

diff --git a/src/broadcom/vulkan/v3dv_cmd_buffer.c b/src/broadcom/vulkan/v3dv_cmd_buffer.c
index ee19717..a14db07 100644 (file)
--- a/src/broadcom/vulkan/v3dv_cmd_buffer.c
+++ b/src/broadcom/vulkan/v3dv_cmd_buffer.c
@@ -2264,11 +2264,14 @@ emit_scissor(struct v3dv_cmd_buffer *cmd_buffer)
     */
    float *vptranslate = dynamic->viewport.translate[0];
    float *vpscale = dynamic->viewport.scale[0];
+   assert(vpscale[0] >= 0);
 
-   float vp_minx = -fabsf(vpscale[0]) + vptranslate[0];
-   float vp_maxx = fabsf(vpscale[0]) + vptranslate[0];
-   float vp_miny = -fabsf(vpscale[1]) + vptranslate[1];
-   float vp_maxy = fabsf(vpscale[1]) + vptranslate[1];
+   float vp_minx = vptranslate[0] - vpscale[0];
+   float vp_maxx = vptranslate[0] + vpscale[0];
+
+   /* With KHR_maintenance1 viewport may have negative Y */
+   float vp_miny = vptranslate[1] - fabsf(vpscale[1]);
+   float vp_maxy = vptranslate[1] + fabsf(vpscale[1]);
 
    /* Quoting from v3dx_emit:
     * "Clip to the scissor if it's enabled, but still clip to the