Mesa (master): i965: fix polygon face orientation when rendering to FBO
Robert Ellison
papillo at kemper.freedesktop.org
Thu Mar 12 03:20:58 UTC 2009
Module: Mesa
Branch: master
Commit: 6dceeb2eb804d708639d68a13a924d65f366458a
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=6dceeb2eb804d708639d68a13a924d65f366458a
Author: Robert Ellison <papillo at vmware.com>
Date: Wed Mar 11 16:27:38 2009 -0600
i965: fix polygon face orientation when rendering to FBO
In the i965, the FBO coordinate system is inverted from the standard
OpenGL/Mesa coordinate system; that means that the viewport and the
polygon face orientation have to be inverted if rendering to a FBO.
The viewport was already being handled correctly; but polygon face
was not. This caused a conform failure when rendering to texture with
two-sided lighting enabled.
This fixes the problem in the i965 driver, and adds to the comment about
the gl_framebuffer "Name" field so that this isn't a surprise to other
driver writers.
---
src/mesa/drivers/dri/i965/brw_sf.c | 10 ++++++++--
src/mesa/main/mtypes.h | 10 +++++++++-
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_sf.c b/src/mesa/drivers/dri/i965/brw_sf.c
index 8c17115..c3c8597 100644
--- a/src/mesa/drivers/dri/i965/brw_sf.c
+++ b/src/mesa/drivers/dri/i965/brw_sf.c
@@ -167,8 +167,14 @@ static void upload_sf_prog(struct brw_context *brw)
key.do_twoside_color = (ctx->Light.Enabled && ctx->Light.Model.TwoSide);
/* _NEW_POLYGON */
- if (key.do_twoside_color)
- key.frontface_ccw = (ctx->Polygon.FrontFace == GL_CCW);
+ if (key.do_twoside_color) {
+ /* If we're rendering to a FBO, we have to invert the polygon
+ * face orientation, just as we invert the viewport in
+ * sf_unit_create_from_key(). ctx->DrawBuffer->Name will be
+ * nonzero if we're rendering to such an FBO.
+ */
+ key.frontface_ccw = (ctx->Polygon.FrontFace == GL_CCW) ^ (ctx->DrawBuffer->Name != 0);
+ }
dri_bo_unreference(brw->sf.prog_bo);
brw->sf.prog_bo = brw_search_cache(&brw->cache, BRW_SF_PROG,
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index f205864..9080c83 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2236,7 +2236,15 @@ struct gl_renderbuffer_attachment
struct gl_framebuffer
{
_glthread_Mutex Mutex; /**< for thread safety */
- GLuint Name; /**< if zero, this is a window system framebuffer */
+ /**
+ * If zero, this is a window system framebuffer. If non-zero, this
+ * is a FBO framebuffer; note that for some devices (i.e. those with
+ * a natural pixel coordinate system for FBOs that differs from the
+ * OpenGL/Mesa coordinate system), this means that both the viewport
+ * and polygon face orientation will have to be inverted.
+ */
+ GLuint Name;
+
GLint RefCount;
GLboolean DeletePending;
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