Add a quad 'bufloop' stage to handle glDrawBuffer(GL_FRONT_AND_BACK).

This removes the notion of multiple color buffers from all other stages.
Will need a bit more work when shaders with multiple render targets arrive.

1 files changed, 59 insertions, 0 deletions

diff --git a/src/mesa/pipe/softpipe/sp_quad_bufloop.c b/src/mesa/pipe/softpipe/sp_quad_bufloop.c
new file mode 100644
index 00000000000..977cc74c263
--- /dev/null
+++ b/src/mesa/pipe/softpipe/sp_quad_bufloop.c
@@ -0,0 +1,59 @@
+
+
+#include "main/glheader.h"
+#include "main/imports.h"
+#include "sp_context.h"
+#include "sp_headers.h"
+#include "sp_surface.h"
+#include "sp_quad.h"
+
+
+/**
+ * Loop over colorbuffers, passing quad to next stage each time.
+ */
+static void
+cbuf_loop_quad(struct quad_stage *qs, struct quad_header *quad)
+{
+   struct softpipe_context *softpipe = qs->softpipe;
+   const GLuint sz = sizeof(quad->outputs.color);
+   GLfloat tmp[4][QUAD_SIZE];
+   GLuint i;
+
+   assert(sz == sizeof(tmp));
+
+   /* make copy of original colors since they can get modified
+    * by blending and masking.
+    */
+   memcpy(tmp, quad->outputs.color, sz);
+
+   for (i = 0; i < softpipe->framebuffer.num_cbufs; i++) {
+      /* set current cbuffer */
+      softpipe->cbuf = softpipe->framebuffer.cbufs[i];
+
+      /* pass blended quad to next stage */
+      qs->next->run(qs->next, quad);
+
+      if (i + 1 < softpipe->framebuffer.num_cbufs) {
+         /* restore quad's colors for next buffer */
+         memcpy(quad->outputs.color, tmp, sz);
+      }
+   }
+
+   softpipe->cbuf = NULL; /* prevent accidental use */
+}
+
+
+/**
+ * Create the colorbuffer loop stage.
+ * This is used to implement GL_FRONT_AND_BACK rendering.
+ */
+struct quad_stage *sp_quad_bufloop_stage( struct softpipe_context *softpipe )
+{
+   struct quad_stage *stage = CALLOC_STRUCT(quad_stage);
+
+   stage->softpipe = softpipe;
+   stage->run = cbuf_loop_quad;
+
+   return stage;
+}
+