[Mesa-dev] [PATCH] intel: FBOs with texture border are unsupported

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

FBOs differ from textures in a significant way.  With textures, we can
strip the border and get correct rendering except when the application
fetches texels outside [0,1].

With an FBO, the pixel at (0,0) is in the border.  The
ARB_framebuffer_object spec says:

    "If the attached image is a texture image, then the window
    coordinates (x[w], y[w]) correspond to the texel (i, j, k), from
    figure 3.10 as follows:

                           i = (x[w] - b)

                           j = (y[w] - b)

                           k = (layer - b)

    where <b> is the texture image's border width..."

Since the border doesn't exist, we can never render any pixels in the
correct location.  Just mark these FBOs FRAMEBUFFER_UNSUPPORTED.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42336
---
 src/mesa/drivers/dri/intel/intel_fbo.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/intel/intel_fbo.c b/src/mesa/drivers/dri/intel/intel_fbo.c
index 2ba43ac..62ed754 100644
--- a/src/mesa/drivers/dri/intel/intel_fbo.c
+++ b/src/mesa/drivers/dri/intel/intel_fbo.c
@@ -746,6 +746,7 @@ intel_validate_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 
    for (i = 0; i < Elements(fb->Attachment); i++) {
       struct gl_renderbuffer *rb;
+      struct gl_texture_object *tex;
       struct intel_renderbuffer *irb;
 
       if (fb->Attachment[i].Type == GL_NONE)
@@ -762,6 +763,18 @@ intel_validate_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 	 continue;
       }
 
+      tex = fb->Attachment[i].Texture;
+      if (tex != NULL) {
+	 const unsigned face = fb->Attachment[i].CubeMapFace;
+	 const unsigned level = fb->Attachment[i].TextureLevel;
+
+	 if (tex->Image[face][level]->Border) {
+	    DBG("texture with border\n");
+	    fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
+	    continue;
+	 }
+      }
+
       irb = intel_renderbuffer(rb);
       if (irb == NULL) {
 	 DBG("software rendering renderbuffer\n");
-- 
1.7.6.4