From 83b589301f4a150f4b1b13fd3ffd9f6d98ee6546 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Tue, 23 Feb 2016 16:15:34 -0700 Subject: [PATCH] st/mesa: fix frontbuffer glReadPixels regressions The change "mesa/readpix: Don't clip in _mesa_readpixels()" caused a few piglit regressions. The failing tests use glReadPixels to read from the front color buffer. The problem is we were trying to read from a non-existant front color buffer. The front color buffer is created on demand in st/mesa. Since the missing buffer bounds were effectively 0 x 0 the glReadPixels was totally clipped and returned early. The fix involves creating the real front color buffer when we're about to try reading from it. Tested with llvmpipe and VMware driver on Linux, Windows. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94253 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94254 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94257 Cc: mesa-stable@lists.freedesktop.org Reviewed-by: Roland Scheidegger --- src/mesa/state_tracker/st_cb_fbo.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/src/mesa/state_tracker/st_cb_fbo.c b/src/mesa/state_tracker/st_cb_fbo.c index 2a2eb0992c8..82ab914503b 100644 --- a/src/mesa/state_tracker/st_cb_fbo.c +++ b/src/mesa/state_tracker/st_cb_fbo.c @@ -44,6 +44,7 @@ #include "pipe/p_context.h" #include "pipe/p_defines.h" #include "pipe/p_screen.h" +#include "st_atom.h" #include "st_context.h" #include "st_cb_fbo.h" #include "st_cb_flush.h" @@ -711,9 +712,17 @@ st_ReadBuffer(struct gl_context *ctx, GLenum buffer) (void) buffer; - /* add the renderbuffer on demand */ - if (fb->_ColorReadBufferIndex >= 0) + /* Check if we need to allocate a front color buffer. + * Front buffers are often allocated on demand (other color buffers are + * always allocated in advance). + */ + if ((fb->_ColorReadBufferIndex == BUFFER_FRONT_LEFT || + fb->_ColorReadBufferIndex == BUFFER_FRONT_RIGHT) && + fb->Attachment[fb->_ColorReadBufferIndex].Type == GL_NONE) { + /* add the buffer */ st_manager_add_color_renderbuffer(st, fb, fb->_ColorReadBufferIndex); + st_validate_state(st, ST_PIPELINE_RENDER); + } }