>From the ARB_gpu_shader5 spec:
"Multiple vertex streams are supported only if the output primitive
type is declared to be "points". A program will fail to link if it
contains a geometry shader calling EmitStreamVertex() or
EndStreamPrimitive() if its output primitive type is not "points".
However, since EmitVertex() == EmitStreamVertex(0) and
EndPrimitive() == EmitEndPrimitive(0), we only fail to link if these
functions are called with a non-zero stream. This is also what Nvidia does.
---
src/glsl/linker.cpp | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 7ff7694..0c42823 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -554,6 +554,35 @@ validate_geometry_shader_executable(struct
gl_shader_program *prog,
find_end_primitive_visitor end_primitive;
end_primitive.run(shader->ir);
prog->Geom.UsesEndPrimitive = end_primitive.end_primitive_found();
+
+ /* From the ARB_gpu_shader5 spec:
+ *
+ * "Multiple vertex streams are supported only if the output primitive
+ * type is declared to be "points". A program will fail to link if it
+ * contains a geometry shader calling EmitStreamVertex() or
+ * EndStreamPrimitive() if its output primitive type is not "points".
+ *
+ * However, in the same spec:
+ *
+ * "The function EmitVertex() is equivalent to calling EmitStreamVertex()
+ * with <stream> set to zero."
+ *
+ * And:
+ *
+ * "The function EndPrimitive() is equivalent to calling
+ * EndStreamPrimitive() with <stream> set to zero."
+ *
+ * Since we can call EmitVertex() and EndPrimitive() when we output
+ * primitives other than points, calling EmitStreamVertex(0) or
+ * EmitEndPrimitive(0) should not produce errors. This it also what Nvidia
+ * does. Currently we only set prog->Geom.UsesStreams to TRUE when
+ * EmitStreamVertex() or EmitEndPrimitive() are called with a non-zero
+ * stream.
+ */
+ if (prog->Geom.UsesStreams && prog->Geom.OutputType != GL_POINTS) {
+ linker_error(prog, "EmitStreamVertex(n) and EndStreamPrimitive(n) "
+ "with n>0 requires point output");
+ }
}
--
1.9.1
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