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cogl-pipeline-opengl: Don't use number of tex units on fixed-function

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The CoglPipeline code uses a combination of GL_MAX_TEXTURE_COORDS,
GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS and GL_MAX_TEXTURE_UNITS to
determine the maximum number of layers to allow in a pipeline. However
on fixed function hardware that doesn't advertise either GLSL or ARBfp
it was still using the first two enums which will probably just return
0 and set a GLerror. This meant that we effectively didn't support
using any layers on purely fixed function hardware. This patch changes
it to only use those two enums if the appropriate extensions are
advertised and to always use GL_MAX_TEXTURE_UNITS except on GLES2
where there is no fixed function.

https://bugzilla.gnome.org/show_bug.cgi?id=650966
This commit is contained in:
Neil Roberts 2011-05-24 13:23:13 +01:00
parent 19e1dcff23
commit d8df30cb9c
1 changed files with 50 additions and 19 deletions
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67
cogl/cogl-pipeline-opengl.c
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@ -646,28 +646,59 @@ get_max_activateable_texture_units (void)
if (G_UNLIKELY (ctx->max_activateable_texture_units == -1))
{
#if defined (HAVE_COGL_GL)
GLint max_tex_coords;
GLint max_combined_tex_units;
GE (glGetIntegerv (GL_MAX_TEXTURE_COORDS, &max_tex_coords));
GLint values[3];
int n_values = 0;
int i;
#ifdef HAVE_COGL_GL
/* GL_MAX_TEXTURE_COORDS is provided for both GLSL and ARBfp. It
defines the number of texture coordinates that can be
uploaded (but doesn't necessarily relate to how many texture
images can be sampled) */
if (cogl_features_available (COGL_FEATURE_SHADERS_GLSL) ||
cogl_features_available (COGL_FEATURE_SHADERS_ARBFP))
/* Previously this code subtracted the value by one but there
was no explanation for why it did this and it doesn't seem
to make sense so it has been removed */
GE (glGetIntegerv (GL_MAX_TEXTURE_COORDS, values + n_values++));
/* GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS is defined for GLSL but
not ARBfp */
if (cogl_features_available (COGL_FEATURE_SHADERS_GLSL))
GE (glGetIntegerv (GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,
&max_combined_tex_units));
ctx->max_activateable_texture_units =
MAX (max_tex_coords - 1, max_combined_tex_units);
#elif defined (HAVE_COGL_GLES2)
GLint max_vertex_attribs;
GLint max_combined_tex_units;
GE (glGetIntegerv (GL_MAX_VERTEX_ATTRIBS, &max_vertex_attribs));
GE (glGetIntegerv (GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,
&max_combined_tex_units));
values + n_values++));
#endif /* HAVE_COGL_GL */
#ifdef HAVE_COGL_GLES2
GE (glGetIntegerv (GL_MAX_VERTEX_ATTRIBS, values + n_values));
/* Two of the vertex attribs need to be used for the position
and color */
ctx->max_activateable_texture_units =
MAX (max_vertex_attribs - 2, max_combined_tex_units);
#else
values[n_values++] -= 2;
GE (glGetIntegerv (GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,
values + n_values++));
#else /* HAVE_COGL_GLES2 */
/* GL_MAX_TEXTURE_UNITS defines the number of units that are
usable from the fixed function pipeline, therefore it isn't
available in GLES2. These are also tied to the number of
texture coordinates that can be uploaded so it should be less
than that available from the shader extensions */
GE (glGetIntegerv (GL_MAX_TEXTURE_UNITS,
&ctx->max_activateable_texture_units));
#endif
values + n_values++));
#endif /* HAVE_COGL_GLES2 */
g_assert (n_values <= G_N_ELEMENTS (values) &&
n_values > 0);
/* Use the maximum value */
ctx->max_activateable_texture_units = values[0];
for (i = 1; i < n_values; i++)
ctx->max_activateable_texture_units =
MAX (values[i], ctx->max_activateable_texture_units);
}
return ctx->max_activateable_texture_units;