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-rw-r--r--src/mesa/main/transformfeedback.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/src/mesa/main/transformfeedback.c b/src/mesa/main/transformfeedback.c
index 22060c34c97..d9c6e514e8f 100644
--- a/src/mesa/main/transformfeedback.c
+++ b/src/mesa/main/transformfeedback.c
@@ -34,6 +34,7 @@
#include "bufferobj.h"
#include "context.h"
#include "hash.h"
+#include "macros.h"
#include "mfeatures.h"
#include "mtypes.h"
#include "transformfeedback.h"
@@ -246,6 +247,34 @@ _mesa_init_transform_feedback_functions(struct dd_function_table *driver)
/**
+ * Compute the maximum number of vertices that can be written to the currently
+ * enabled transform feedback buffers without overflowing any of them.
+ */
+unsigned
+_mesa_compute_max_transform_feedback_vertices(
+ const struct gl_transform_feedback_object *obj,
+ const struct gl_transform_feedback_info *info)
+{
+ unsigned max_index = 0xffffffff;
+ unsigned i;
+
+ for (i = 0; i < info->NumBuffers; ++i) {
+ unsigned stride = info->BufferStride[i];
+ unsigned max_for_this_buffer;
+
+ /* Skip any inactive buffers, which have a stride of 0. */
+ if (stride == 0)
+ continue;
+
+ max_for_this_buffer = obj->Size[i] / (4 * stride);
+ max_index = MIN2(max_index, max_for_this_buffer);
+ }
+
+ return max_index;
+}
+
+
+/**
** Begin API functions
**/