Re: [Piglit] [PATCH] ext_render_snorm-render: fix read back assumptions

[Tapani Pälli]

On 29.08.2018 00:23, Nanley Chery wrote:
On Tue, Aug 28, 2018 at 09:58:14AM +0300, Tapani Pälli wrote:
Test assumed that we can read back directly from R8, RG8 fbo but
this is not actually enabled by the extension. Patch introduces
additional read from window to sanity check fbo contents.


I think we're allowed to read from R8 and RG8 SNORM FBOs. Page 340 of
the GLES 3.1 spec says that apps can query the driver to find out which
formats are supported for ReadPixels:

    The second is an implementation-chosen format from among those
    defined in table 8.2, excluding formats DEPTH_COMPONENT and
    DEPTH_STENCIL. The values of format and type for this format may be
    determined by calling GetIntegerv with the symbolic constants
    IMPLEMENTATION_COLOR_READ_FORMAT and IMPLEMENTATION_COLOR_READ_TYPE,
    respectively. The implementation-chosen format may vary depending on
    the format of the selected read buffer of the currently bound read
    framebuffer.

Table 8.2 has entries for R8 and RG8 SNORM.

Maybe the issue is that reading should be allowed only to matching 
number of components with GL_BYTE? I'm currently reading every format as 
GL_RGBA but I could change to use GL_RED, GL_RG, GL_RGBA depending on 
the base format. If I enforce such rules for GL_BYTE formats in Mesa the 
rest of failing dEQP tests start to pass. So for example, reading fbo 
with internalFormat of GL_R8_SNORM would require:

glReadPixels(0, 0, w, h, GL_RED, GL_BYTE, pix);

Does this make sense?



-Nanley

Signed-off-by: Tapani Pälli <tapani.pa...@intel.com>
---
  tests/spec/ext_render_snorm/render.c | 32 ++++++++++++++++++++++++++++----
  1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/tests/spec/ext_render_snorm/render.c 
b/tests/spec/ext_render_snorm/render.c
index 1d4a69c2d..ad309f17c 100644
--- a/tests/spec/ext_render_snorm/render.c
+++ b/tests/spec/ext_render_snorm/render.c
@@ -82,10 +82,11 @@ static const struct fmt_test {
        GLenum iformat;
        GLenum base_format;
        unsigned bpp;
+       bool can_read;
  } tests[] = {
-       { GL_R8_SNORM,          GL_RED,         1, },
-       { GL_RG8_SNORM,         GL_RG,          2, },
-       { GL_RGBA8_SNORM,       GL_RGBA,        4, },
+       { GL_R8_SNORM,          GL_RED,         1,      false },
+       { GL_RG8_SNORM,         GL_RG,          2,      false },
+       { GL_RGBA8_SNORM,       GL_RGBA,        4,      true  },
  };
  
  static GLuint prog;
@@ -229,6 +230,25 @@ verify_contents(const struct fmt_test *test)
        return result;
  }
  
+static bool
+verify_contents_float(const struct fmt_test *test)
+{
+       /* Setup expected value, alpha is always max in the test. */
+       char value[4] = { 0, 0, 0, SCHAR_MAX };
+       value_for_format(test, value);
+
+       const float expected[4] = {
+               value[0] / SCHAR_MAX,
+               value[1] / SCHAR_MAX,
+               value[2] / SCHAR_MAX,
+               value[3] / SCHAR_MAX,
+       };
+
+       bool res = piglit_probe_rect_rgba(0, 0, piglit_width, piglit_height,
+                                         expected);
+       return res;
+}
+
  static bool
  test_format(const struct fmt_test *test)
  {
@@ -282,13 +302,17 @@ test_format(const struct fmt_test *test)
        glDeleteTextures(1, &tmp_tex);
  
  	/* Verify contents. */
-       pass &= verify_contents(test);
+       if (test->can_read)
+               pass &= verify_contents(test);
  
  	glDeleteFramebuffers(1, &fbo);
  
  	/* Render fbo contents to window. */
        render_texture(fbo_tex, GL_TEXTURE_2D, 0);
  
+	/* Verify window contents. */
+       pass &= verify_contents_float(test);
+
        piglit_present_results();
  
  	glDeleteTextures(1, &fbo_tex);
--
2.14.4

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