[Mesa-dev] [PATCH] meta: Handle array textures in scaled MSAA blits

[Ian Romanick]

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

The old code had some significant problems with respect to
sampler2DArray textures.  The biggest problem was that some of the code
would use vec3 for the texture coordinate type, and other parts of the
code would use vec2.  The resulting shader would not even compile.
Since there were not tests for this path, nobody noticed.

The input to the fragment shader is always treated as a vec3.  If the
source data is only vec2, the vertex puller will supply 0 for the .z
component.  The texture coordinate passed to the fragment shader is
always a vec2 that comes from the .xy part of the vertex shader input.
The layer, taken from the .z of the vertex shader input is passed
separately as a flat integer.  If the generated fragment shader does not
use the layer integer, the GLSL linker will eliminate all the dead code
in the vertex shader.

Fixes the new piglit tests "blit-scaled samples=2 with
gl_texture_2d_multisample_array", etc. on i965.

Note for stable maintainer: This patch may depend on 46037237, and that
patch should be safe for stable.

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>
Cc: "10.6 11.0" <mesa-stable at lists.freedesktop.org>
---
This is currently running through our Jenkins server.  There were no
regressions on my BDW system.

 src/mesa/drivers/common/meta_blit.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/src/mesa/drivers/common/meta_blit.c b/src/mesa/drivers/common/meta_blit.c
index a41fe42..5972a5a 100644
--- a/src/mesa/drivers/common/meta_blit.c
+++ b/src/mesa/drivers/common/meta_blit.c
@@ -71,9 +71,7 @@ setup_glsl_msaa_blit_scaled_shader(struct gl_context *ctx,
    char *sample_map_str = rzalloc_size(mem_ctx, 1);
    char *sample_map_expr = rzalloc_size(mem_ctx, 1);
    char *texel_fetch_macro = rzalloc_size(mem_ctx, 1);
-   const char *vs_source;
    const char *sampler_array_suffix = "";
-   const char *texcoord_type = "vec2";
    float y_scale;
    enum blit_msaa_shader shader_index;
 
@@ -99,7 +97,6 @@ setup_glsl_msaa_blit_scaled_shader(struct gl_context *ctx,
       shader_index += BLIT_2X_MSAA_SHADER_2D_MULTISAMPLE_ARRAY_SCALED_RESOLVE -
                       BLIT_2X_MSAA_SHADER_2D_MULTISAMPLE_SCALED_RESOLVE;
       sampler_array_suffix = "Array";
-      texcoord_type = "vec3";
    }
 
    if (blit->msaa_shaders[shader_index]) {
@@ -150,28 +147,37 @@ setup_glsl_msaa_blit_scaled_shader(struct gl_context *ctx,
                           "   const int sample_map[%d] = int[%d](%s);\n",
                           samples, samples, sample_map_str);
 
-   ralloc_asprintf_append(&texel_fetch_macro,
-                          "#define TEXEL_FETCH(coord) texelFetch(texSampler, i%s(coord), %s);\n",
-                          texcoord_type, sample_number);
+   if (target == GL_TEXTURE_2D_MULTISAMPLE) {
+      ralloc_asprintf_append(&texel_fetch_macro,
+                             "#define TEXEL_FETCH(coord) texelFetch(texSampler, ivec2(coord), %s);\n",
+                             sample_number);
+   } else {
+      ralloc_asprintf_append(&texel_fetch_macro,
+                             "#define TEXEL_FETCH(coord) texelFetch(texSampler, ivec3(coord, layer), %s);\n",
+                             sample_number);
+   }
 
-   vs_source = ralloc_asprintf(mem_ctx,
+   static const char vs_source[] =
                                "#version 130\n"
                                "in vec2 position;\n"
-                               "in %s textureCoords;\n"
-                               "out %s texCoords;\n"
+                               "in vec3 textureCoords;\n"
+                               "out vec2 texCoords;\n"
+                               "flat out int layer;\n"
                                "void main()\n"
                                "{\n"
-                               "   texCoords = textureCoords;\n"
+                               "   texCoords = textureCoords.xy;\n"
+                               "   layer = int(textureCoords.z);\n"
                                "   gl_Position = vec4(position, 0.0, 1.0);\n"
-                               "}\n",
-                               texcoord_type,
-                               texcoord_type);
+                               "}\n"
+      ;
+
    fs_source = ralloc_asprintf(mem_ctx,
                                "#version 130\n"
                                "#extension GL_ARB_texture_multisample : enable\n"
                                "uniform sampler2DMS%s texSampler;\n"
                                "uniform float src_width, src_height;\n"
-                               "in %s texCoords;\n"
+                               "in vec2 texCoords;\n"
+                               "flat in int layer;\n"
                                "out vec4 out_color;\n"
                                "\n"
                                "void main()\n"
@@ -212,7 +218,6 @@ setup_glsl_msaa_blit_scaled_shader(struct gl_context *ctx,
                                "   out_color = mix(x_0_color, x_1_color, interp.y);\n"
                                "}\n",
                                sampler_array_suffix,
-                               texcoord_type,
                                sample_map_expr,
                                y_scale,
                                1.0f / y_scale,
-- 
2.1.0