On 10/23/2011 01:19 PM, Marek Olšák wrote:
On Sat, Oct 22, 2011 at 2:14 AM, Dan McCabe<zen3d.li...@gmail.com> wrote:
Modify the linker to assign additional slots for varying
variables used by transform feedback. This is done after other
varyings are already assigned slots.
Since this is done after previous varying slot assignments,
the code needs to know how many varyings are already assigned
slots. A new function "max_varying()" is introduced to examine a
previously processed shader to find the largest varying already
assigned a slot. All new varyings will be assigned slots after
this one. If varyings are found, -1 is returned.
---
src/glsl/linker.cpp | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index a7c38a3..81f2658 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -207,6 +207,25 @@ invalidate_variable_locations(gl_shader *sh, enum
ir_variable_mode mode,
}
}
+
+int
+max_varying(gl_shader *sh, enum ir_variable_mode mode)
+{
+ int max_varying = -1;
+
+ foreach_list(node, sh->ir) {
+ ir_variable *const var = ((ir_instruction *) node)->as_variable();
+
+ if ((var == NULL) || (var->mode != (unsigned) mode))
+ continue;
+
+ if (var->location> max_varying)
+ max_varying = var->location;
+ }
+
+ return max_varying;
+}
+
/**
* Determine the number of attribute slots required for a particular type
@@ -1597,6 +1616,69 @@ assign_varying_locations(struct gl_context *ctx,
void
+assign_transform_feedback_varying_locations(struct gl_context *ctx,
+ struct gl_shader_program *prog)
+{
+ struct gl_shader *vs = prog->_LinkedShaders[MESA_SHADER_VERTEX];
+
+ if (vs == NULL)
+ return;
+
+ char **names = prog->TransformFeedback.VaryingNames;
+ int num_names = prog->TransformFeedback.NumVarying;
+
+ if (num_names<= 0)
+ return;
+
+ int num_varying = max_varying(vs, ir_var_out) + 1;
+ unsigned output_index =
+ (num_varying> VERT_RESULT_VAR0)
+ ? num_varying
+ : VERT_RESULT_VAR0;
+
+ foreach_list(node, vs->ir) {
+ ir_variable *const output_var = ((ir_instruction *) node)->as_variable();
+
+ if (output_var == NULL
+ || output_var->mode != ir_var_out
+ || output_var->location != -1)
+ continue;
+
+ /* Find a transform feedback varying variable that has
+ * the same name as the shader variable.
+ */
+ int varying_index = -1;
+ for (int num_name = 0; num_name< num_names; num_name++) {
+ char *name = *names++;
Hi Dan,
Sorry for the very late reply and thank you very much for the work. I
have just a few remarks.
1) *names++ doesn't seem correct and causes a segfault. You probably
wanted *(names++). I fixed this in my code by using names[num_name],
which is more readable.
Agreed on both points. Thanks.
2) I am not sure whether your code will work with varying arrays. With
"varying vec4 array[2];", "array[0]" and "array[1]" are possible names
for transform feedback varyings.
Possibly not; this hasn't been tested extensively. But I'll check.
3) If a transform feedback varying is undeclared, linker_error should
be called and the linker should back off.
Agreed.
Other than that, transform feedback varying locations seem to be
assigned correctly.
Best regards,
Marek
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