[Mesa-dev] [PATCH] mesa: Round float param in glTexparameterf() to nearest integer

[Anuj Phogat]

OpenGL 4.2 specification suggests rounding the float data to nearest
integer when the type of internal state is integer. Out of range floats
should be clamped to {INT_MIN, INT_MAX}. This is not specified anywhere
in gl/gles spec but below test expects this behavior.
This patch makes gles3 conformance sgis_texture_lod_basic_getter.test pass.

A GL spec bug will be raised to include clamping of out of range floats.

V2: Round float to nearest integer for all cases where _mesa_Texparameterf()
converts float param to int. Use the same block of float to int conversion
code for GL_TEXTURE_SWIZZLE_{R,G,B,A}_EXT cases as well.

Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
---
 src/mesa/main/texparam.c |   13 ++++---------
 1 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/mesa/main/texparam.c b/src/mesa/main/texparam.c
index ca5a21f..4d32fd6 100644
--- a/src/mesa/main/texparam.c
+++ b/src/mesa/main/texparam.c
@@ -662,21 +662,16 @@ _mesa_TexParameterf(GLenum target, GLenum pname, GLfloat param)
    case GL_DEPTH_TEXTURE_MODE_ARB:
    case GL_TEXTURE_SRGB_DECODE_EXT:
    case GL_TEXTURE_CUBE_MAP_SEAMLESS:
-      {
-         /* convert float param to int */
-         GLint p[4];
-         p[0] = (GLint) param;
-         p[1] = p[2] = p[3] = 0;
-         need_update = set_tex_parameteri(ctx, texObj, pname, p);
-      }
-      break;
    case GL_TEXTURE_SWIZZLE_R_EXT:
    case GL_TEXTURE_SWIZZLE_G_EXT:
    case GL_TEXTURE_SWIZZLE_B_EXT:
    case GL_TEXTURE_SWIZZLE_A_EXT:
       {
          GLint p[4];
-         p[0] = (GLint) param;
+         p[0] = (param > 0) ?
+                ((param > INT_MAX) ? INT_MAX : (GLint) (param + 0.5)) :
+                ((param < INT_MIN) ? INT_MIN : (GLint) (param - 0.5));
+
          p[1] = p[2] = p[3] = 0;
          need_update = set_tex_parameteri(ctx, texObj, pname, p);
       }
-- 
1.7.7.6