[Mesa-dev] [PATCH v4 (part2) 45/59] glsl: fix UNIFORM_BUFFER_START or UNIFORM_BUFFER_SIZE query when no buffer object is bound

[Tapani Pälli]

Reviewed-by: Tapani Pälli <tapani.palli at intel.com>

On 08/05/2015 11:30 AM, Iago Toral Quiroga wrote:
> From: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
>
> According to ARB_uniform_buffer_object spec:
>
> "If the parameter (starting offset or size) was not specified when the
>   buffer object was bound (e.g. if bound with BindBufferBase), or if no
>   buffer object is bound to <index>, zero is returned."

BTW it seems that this was changed from OpenGL 4.1 to 4.2 (?) for 
UNIFORM_BUFFER_SIZE 4.1 core spec still says

"If the parameter (starting offset or size) was not specified when the 
buffer object was bound, zero is returned. If no buffer object is bound 
to index, -1 is returned"

while 4.2 changed "If not buffer object is bound to index" value to 0, 
GLES 3.1 also says 0.

> Signed-off-by: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
> ---
>   src/mesa/main/get.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/src/mesa/main/get.c b/src/mesa/main/get.c
> index e2bfb5f..b89c49f 100644
> --- a/src/mesa/main/get.c
> +++ b/src/mesa/main/get.c
> @@ -1925,7 +1925,8 @@ find_value_indexed(const char *func, GLenum pname, GLuint index, union value *v)
>   	 goto invalid_value;
>         if (!ctx->Extensions.ARB_uniform_buffer_object)
>   	 goto invalid_enum;
> -      v->value_int = ctx->UniformBufferBindings[index].Offset;
> +      v->value_int = ctx->UniformBufferBindings[index].Offset < 0 ? 0 :
> +                     ctx->UniformBufferBindings[index].Offset;
>         return TYPE_INT;
>   
>      case GL_UNIFORM_BUFFER_SIZE:
> @@ -1933,7 +1934,8 @@ find_value_indexed(const char *func, GLenum pname, GLuint index, union value *v)
>   	 goto invalid_value;
>         if (!ctx->Extensions.ARB_uniform_buffer_object)
>   	 goto invalid_enum;
> -      v->value_int = ctx->UniformBufferBindings[index].Size;
> +      v->value_int = ctx->UniformBufferBindings[index].Size < 0 ? 0 :
> +                     ctx->UniformBufferBindings[index].Size;
>         return TYPE_INT;
>   
>      /* ARB_shader_storage_buffer_object */