scissor depends on glScissor() and framebuffer size

1 files changed, 28 insertions, 9 deletions

diff --git a/src/mesa/softpipe/state_tracker/st_atom_scissor.c b/src/mesa/softpipe/state_tracker/st_atom_scissor.c
index 74f5cc1a2b..105c2a6dd9 100644
--- a/src/mesa/softpipe/state_tracker/st_atom_scissor.c
+++ b/src/mesa/softpipe/state_tracker/st_atom_scissor.c
@@ -36,28 +36,47 @@
 #include "st_atom.h"
 
 
-/* scissor state
+/**
+ * Scissor depends on the scissor box, and the framebuffer dimensions.
  */
-static void update_scissor( struct st_context *st )
+static void
+update_scissor( struct st_context *st )
 {
    struct softpipe_scissor_rect scissor;
+   const struct gl_framebuffer *fb = st->ctx->DrawBuffer;
+
+   scissor.minx = 0;
+   scissor.miny = 0;
+   scissor.maxx = fb->Width;
+   scissor.maxy = fb->Height;
+
+   if (st->ctx->Scissor.Enabled) {
+      if (st->ctx->Scissor.X > scissor.minx)
+         scissor.minx = st->ctx->Scissor.X;
+      if (st->ctx->Scissor.Y > scissor.miny)
+         scissor.miny = st->ctx->Scissor.Y;
+
+      if (st->ctx->Scissor.X + st->ctx->Scissor.Width < scissor.maxx)
+         scissor.maxx = st->ctx->Scissor.X + st->ctx->Scissor.Width;
+      if (st->ctx->Scissor.Y + st->ctx->Scissor.Height < scissor.maxy)
+         scissor.maxy = st->ctx->Scissor.Y + st->ctx->Scissor.Height;
+
+      /* check for null space */
+      if (scissor.minx >= scissor.maxx || scissor.miny >= scissor.maxy)
+         scissor.minx = scissor.miny = scissor.maxx = scissor.maxy = 0;
+   }
 
-   scissor.minx = st->ctx->Scissor.X;
-   scissor.miny = st->ctx->Scissor.Y;
-   scissor.maxx = st->ctx->Scissor.X + st->ctx->Scissor.Width;
-   scissor.maxy = st->ctx->Scissor.Y + st->ctx->Scissor.Height;
-      
    if (memcmp(&scissor, &st->state.scissor, sizeof(scissor)) != 0) {
       /* state has changed */
       st->state.scissor = scissor;  /* struct copy */
-      st->softpipe->set_scissor_rect(st->softpipe, &scissor); /* set new state */
+      st->softpipe->set_scissor_rect(st->softpipe, &scissor); /* activate */
    }
 }
 
 
 const struct st_tracked_state st_update_scissor = {
    .dirty = {
-      .mesa = (_NEW_SCISSOR),
+      .mesa = (_NEW_SCISSOR | _NEW_BUFFERS),
       .st  = 0,
    },
    .update = update_scissor