[Mesa-dev] [PATCH] meta: Use result of texture coordinate clamping operation

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

Previously the result of the complicated clamp() expression just dropped
on the floor: clamp does not modify any of its parameters.  Looking at
the surrounding code, I believe this is supposed to modify the value of
tex_coord.

This change (along with a change to avoid the use of
brw_blorp_framebuffer) does not affect any existing piglit tests.  I'm
not sure what this clamp is trying to accomplish, so I'm not sure how to
write a test to exercise this path.

I also noticed another bug in this code.  There is no way the array
texture case could possibly work.  This will generate code for the
TEXEL_FETCH macro like:

    #define TEXEL_FETCH(coord) texelFetch(texSampler, ivec3(coord), sample_map[int(2 * fract(coord.x))]);

Since the coord parameter of this macro is a vec2 at all invocations, no
expansion of this macro will even compile.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: Anuj Phogat <anuj.phogat at gmail.com>
Cc: Topi Pohjolainen <topi.pohjolainen at intel.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
---
 src/mesa/drivers/common/meta_blit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/common/meta_blit.c b/src/mesa/drivers/common/meta_blit.c
index 71d18de..a41fe42 100644
--- a/src/mesa/drivers/common/meta_blit.c
+++ b/src/mesa/drivers/common/meta_blit.c
@@ -187,8 +187,8 @@ setup_glsl_msaa_blit_scaled_shader(struct gl_context *ctx,
                                "   vec2 tex_coord = texCoords - s_0_offset;\n"
                                "\n"
                                "   tex_coord *= scale;\n"
-                               "   clamp(tex_coord.x, 0.0f, scale.x * src_width - 1.0f);\n"
-                               "   clamp(tex_coord.y, 0.0f, scale.y * src_height - 1.0f);\n"
+                               "   tex_coord.x = clamp(tex_coord.x, 0.0f, scale.x * src_width - 1.0f);\n"
+                               "   tex_coord.y = clamp(tex_coord.y, 0.0f, scale.y * src_height - 1.0f);\n"
                                "   interp = fract(tex_coord);\n"
                                "   tex_coord = ivec2(tex_coord) * scale_inv;\n"
                                "\n"
-- 
2.1.0