gallium: add polygon offset clamp state

This is required for D3D1x and supported by hardware.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/draw/draw_pipe_offset.c b/src/gallium/auxiliary/draw/draw_pipe_offset.c
index 8afbbfa1569..3da52b10624 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_offset.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_offset.c
@@ -43,6 +43,7 @@ struct offset_stage {
 
    float scale;
    float units;
+   float clamp;
 };
 
 
@@ -90,6 +91,10 @@ static void do_offset_tri( struct draw_stage *stage,
 
    float zoffset = offset->units + MAX2(dzdx, dzdy) * offset->scale;
 
+   if (offset->clamp)
+      zoffset = (offset->clamp < 0.0f) ? MAX2(zoffset, offset->clamp) :
+                                         MIN2(zoffset, offset->clamp);
+
    /*
     * Note: we're applying the offset and clamping per-vertex.
     * Ideally, the offset is applied per-fragment prior to fragment shading.
@@ -125,6 +130,7 @@ static void offset_first_tri( struct draw_stage *stage,
 
    offset->units = (float) (stage->draw->rasterizer->offset_units * stage->draw->mrd);
    offset->scale = stage->draw->rasterizer->offset_scale;
+   offset->clamp = stage->draw->rasterizer->offset_clamp;
 
    stage->tri = offset_tri;
    stage->tri( stage, header );