Flush matrices in the progend and flip with a vector

Previously flushing the matrices was performed as part of the
framebuffer state. When on GLES2 this matrix flushing is actually
diverted so that it only keeps a reference to the intended matrix
stack. This is necessary because on GLES2 there are no builtin
uniforms so it can't actually flush the matrices until the program for
the pipeline is generated. When the matrices are flushed it would
store the age of modifications on the matrix stack so that it could
detect when the matrix hasn't changed and avoid flushing it.

This patch changes it so that the pipeline is responsible for flushing
the matrices even when we are using the GL builtins. The same
mechanism for detecting unmodified matrix stacks is used in all
cases. There is a new CoglMatrixStackCache type which is used to store
a reference to the intended matrix stack along with its last flushed
age. There are now two of these attached to the CoglContext to track
the flushed state for the global matrix builtins and also two for each
glsl progend program state to track the flushed state for a
program. The framebuffer matrix flush now just updates the intended
matrix stacks without actually trying to flush.

When a vertex snippet is attached to the pipeline, the GLSL vertend
will now avoid using the projection matrix to flip the rendering. This
is necessary because any vertex snippet may cause the projection
matrix not to be used. Instead the flip is done as a forced final step
by multiplying cogl_position_out by a vec4 uniform. This uniform is
updated as part of the progend pre_paint depending on whether the
framebuffer is offscreen or not.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

1 files changed, 17 insertions, 5 deletions

diff --git a/cogl/cogl-pipeline-private.h b/cogl/cogl-pipeline-private.h
index 8e7f3213..f676b1a0 100644
--- a/cogl/cogl-pipeline-private.h
+++ b/cogl/cogl-pipeline-private.h
@@ -137,11 +137,21 @@
 
 /* If we have either of the GLSL backends then we also need a GLSL
    progend to combine the shaders generated into a single
-   program. Currently there is only one progend but if we ever add
-   other languages they would likely need their own progend too. The
-   progends are different from the other backends because there can be
-   more than one in use for each pipeline. All of the progends are
-   invoked whenever a pipeline is flushed. */
+   program. Same goes for the fixed progends which are used to flush
+   the matrices */
+#ifdef COGL_PIPELINE_FRAGEND_FIXED
+
+#define COGL_PIPELINE_PROGEND_FIXED      0
+
+#ifdef COGL_PIPELINE_FRAGEND_GLSL
+#define COGL_PIPELINE_PROGEND_GLSL       1
+#define COGL_PIPELINE_N_PROGENDS         2
+#else
+#define COGL_PIPELINE_N_PROGENDS         1
+#endif
+
+#else /* COGL_PIPELINE_FRAGEND_FIXED */
+
 #ifdef COGL_PIPELINE_FRAGEND_GLSL
 #define COGL_PIPELINE_PROGEND_GLSL       0
 #define COGL_PIPELINE_N_PROGENDS         1
@@ -149,6 +159,8 @@
 #define COGL_PIPELINE_N_PROGENDS         0
 #endif
 
+#endif /* COGL_PIPELINE_FRAGEND_FIXED */
+
 /* XXX: should I rename these as
  * COGL_PIPELINE_STATE_INDEX_XYZ... ?
  */