[Mesa-dev] [PATCH v2] mesa/st: hardcode the viewport bounds range

[Ilia Mirkin]

The bound range is disconnected from the viewport dimensions. This is
the relevant bit from glViewportArray:

"""
The location of the viewport's bottom left corner, given by (x, y) is
clamped to be within the implementaiton-dependent viewport bounds range.
The viewport bounds range [min, max] can be determined by calling glGet
with argument GL_VIEWPORT_BOUNDS_RANGE. Viewport width and height are
silently clamped to a range that depends on the implementation. To query
this range, call glGet with argument GL_MAX_VIEWPORT_DIMS.
"""

Just set it to +/-16384, as that is the minimum required by
ARB_viewport_array and the value that all current drivers provide.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---
 src/mesa/state_tracker/st_extensions.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
index 1f391c9..c54b18b 100644
--- a/src/mesa/state_tracker/st_extensions.c
+++ b/src/mesa/state_tracker/st_extensions.c
@@ -783,8 +783,8 @@ void st_init_extensions(struct st_context *st)
    if (ctx->API == API_OPENGL_CORE) {
       ctx->Const.MaxViewports = screen->get_param(screen, PIPE_CAP_MAX_VIEWPORTS);
       if (ctx->Const.MaxViewports >= 16) {
-         ctx->Const.ViewportBounds.Min = -(float)ctx->Const.MaxViewportWidth;
-         ctx->Const.ViewportBounds.Max = ctx->Const.MaxViewportWidth;
+         ctx->Const.ViewportBounds.Min = -16384.0;
+         ctx->Const.ViewportBounds.Max = 16384.0;
          ctx->Extensions.ARB_viewport_array = GL_TRUE;
       }
    }
-- 
1.8.3.2