[Mesa-dev] [RFC 22/63] mesa/formatquery: Added a func to check <internalformat> supported

[Eduardo Lima Mitev]

From: Antia Puentes <apuentes at igalia.com>

>From the ARB_internalformat_query2 specification:

  "The INTERNALFORMAT_SUPPORTED <pname> can be used to determine if
   the internal format is supported, and the  other <pnames> are defined
   in terms of whether or not the format is supported."
---
 src/mesa/main/formatquery.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/src/mesa/main/formatquery.c b/src/mesa/main/formatquery.c
index c1734f5..11bf133 100644
--- a/src/mesa/main/formatquery.c
+++ b/src/mesa/main/formatquery.c
@@ -525,6 +525,39 @@ _is_resource_supported(struct gl_context *ctx, GLenum target,
    return true;
 }
 
+static bool
+_is_internalformat_supported(struct gl_context *ctx, GLenum target,
+                             GLenum internalformat)
+{
+   /* From the ARB_internalformat_query2 specification:
+    *
+    *     "- INTERNALFORMAT_SUPPORTED: If <internalformat> is an internal format
+    *     that is supported by the implementation in at least some subset of
+    *     possible operations, TRUE is written to <params>.  If <internalformat>
+    *     if not a valid token for any internal format usage, FALSE is returned.
+    *
+    *     <internalformats> that must be supported (in GL 4.2 or later) include
+    *      the following:
+    *         - "sized internal formats" from Table 3.12, 3.13, and 3.15,
+    *         - any specific "compressed internal format" from Table 3.14,
+    *         - any "image unit format" from Table 3.21.
+    *         - any generic "compressed internal format" from Table 3.14, if the
+    *         implementation accepts it for any texture specification commands, and
+    *         - unsized or base internal format, if the implementation accepts
+    *         it for texture or image specification.
+    */
+   GLint buffer[1];
+
+   if (_mesa_base_tex_format(ctx, internalformat) < 0)
+      return false;
+
+   /* Let the driver have the final word */
+   ctx->Driver.QueryInternalFormat(ctx, target, internalformat,
+                                   GL_INTERNALFORMAT_SUPPORTED, buffer);
+
+   return (buffer[0] == GL_TRUE);
+}
+
 /* default implementation of QueryInternalFormat driverfunc, for
  * drivers not implementing ARB_internalformat_query2.
  */
@@ -577,6 +610,7 @@ _mesa_GetInternalformativ(GLenum target, GLenum internalformat, GLenum pname,
    _set_default_response(pname, buffer);
 
    if (!_is_target_supported(ctx, target) ||
+       !_is_internalformat_supported(ctx, target, internalformat) ||
        !_is_resource_supported(ctx, target, internalformat, pname))
       goto end;
 
-- 
2.5.3