[Mesa-dev] [RFC 56/63] mesa/formatquery: added FILTER pname support

[Eduardo Lima Mitev]

From: Alejandro Piñeiro <apinheiro at igalia.com>

It discards out the targets and internalformats that explicitly
mention (per-spec) that doesn't support filter types other than
NEAREST or NEAREST_MIPMAP_NEAREST. Those are:

  * Texture buffers target
  * Multisample targets
  * Any integer internalformat

For the case of multisample targets, it was used the existing method
_mesa_target_allows_setting_sampler_parameter. This would scalate
better in the future if new targets appear that doesn't allow to
set sampler parameters.

We consider RENDERBUFFER to support LINEAR filters, because although
it doesn't support this filter for sampling, you can set LINEAR
on a blit operation using glBlitFramebuffer.
---
 src/mesa/main/formatquery.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/mesa/main/formatquery.c b/src/mesa/main/formatquery.c
index d720fc2..8674af3 100644
--- a/src/mesa/main/formatquery.c
+++ b/src/mesa/main/formatquery.c
@@ -640,6 +640,7 @@ _mesa_query_internal_format_default(struct gl_context *ctx, GLenum target,
    case GL_FRAMEBUFFER_RENDERABLE:
    case GL_FRAMEBUFFER_RENDERABLE_LAYERED:
    case GL_FRAMEBUFFER_BLEND:
+   case GL_FILTER:
       params[0] = GL_FULL_SUPPORT;
       break;
 
@@ -1164,7 +1165,24 @@ _mesa_GetInternalformativ(GLenum target, GLenum internalformat, GLenum pname,
       break;
 
    case GL_FILTER:
-      /* @TODO */
+      /* If it doesn't allow to set sampler parameters then it would not allow
+       * to set a filter different to GL_NEAREST. In practice, this method
+       * only filters out MULTISAMPLE/MULTISAMPLE_ARRAY */
+      if (!_mesa_target_allows_setting_sampler_parameters(target))
+         goto end;
+
+      if (_mesa_is_enum_format_integer(internalformat))
+         goto end;
+
+      if (target == GL_TEXTURE_BUFFER)
+         goto end;
+
+      /* At this point we know that multi-texel filtering is supported. We
+       * need to call the driver to know if it is CAVEAT_SUPPORT or
+       * FULL_SUPPORT.
+       */
+      ctx->Driver.QueryInternalFormat(ctx, target, internalformat, pname,
+                                      buffer);
       break;
 
    case GL_VERTEX_TEXTURE:
-- 
2.5.3