glamor_init: clamp GLSL to 120 if platform doesn't have instanced arrays
Lukas F. Hartmann
lukas at mntmn.com
Tue May 15 19:51:56 UTC 2018
Hi,
I upgraded Xwayland and the assorted libraries from git masters today,
and noticed that glamor wouldn't work anymore on i.MX6/etnaviv. The
error was:
No provider of glVertexAttribDivisor found. Requires one of:
Desktop OpenGL 3.3
OpenGL ES 3.0
GL extension "GL_ANGLE_instanced_arrays"
GL extension "GL_ARB_instanced_arrays"
GL extension "GL_EXT_instanced_arrays"
GL extension "GL_NV_instanced_arrays"
The problem is that etnaviv offers GLSL 140 on GL 2.1 and glamor
rendering assumes that glVertexAttribDivisor() is always available on
GLSL>=130, which is not the case here. Forcing GLSL 120 makes glamor
work fine again on this platform. After chatting with ajax in
#xorg-devel, the following solution was proposed.
This is my first time of submitting a patch, so please excuse me and
advise if I'm doing it wrong ;)
Cheers
Lukas (mntmn)
---
glamor/glamor.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/glamor/glamor.c b/glamor/glamor.c
index 86935ed..d984d20 100644
--- a/glamor/glamor.c
+++ b/glamor/glamor.c
@@ -563,6 +563,14 @@ glamor_init(ScreenPtr screen, unsigned int flags)
if (!glamor_check_instruction_count(gl_version))
goto fail;
+
+ /* Glamor rendering assumes that platforms with GLSL 130+
+ * have instanced arrays, but this is not always the case.
+ * etnaviv offers GLSL 140 with OpenGL 2.1.
+ */
+ if (glamor_priv->glsl_version >= 130 &&
+ !epoxy_has_gl_extension("GL_ARB_instanced_arrays"))
+ glamor_priv->glsl_version = 120;
} else {
if (gl_version < 20) {
ErrorF("Require Open GLES2.0 or later.\n");
--
2.15.1
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