[Bf-blender-cvs] [1b8e1bb6351] blender2.8: DRW: Add polygon offset mode.

[Clément Foucault]

Commit: 1b8e1bb6351415912d7106bca6488c6c0dd50cc3
Author: Clément Foucault
Date:   Tue Dec 11 18:18:36 2018 +0100
Branches: blender2.8
https://developer.blender.org/rB1b8e1bb6351415912d7106bca6488c6c0dd50cc3

DRW: Add polygon offset mode.

===================================================================

M	source/blender/draw/intern/DRW_render.h
M	source/blender/draw/intern/draw_manager_exec.c

===================================================================

diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index 519c907a6a4..89aa55c56b2 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -283,8 +283,8 @@ typedef enum {
 	DRW_STATE_CULL_FRONT    = (1 << 9),
 	DRW_STATE_WIRE          = (1 << 10),
 	DRW_STATE_POINT         = (1 << 11),
-	/* DRW_STATE_STIPPLE_2     = (1 << 12), */ /* Not used */
-	/* DRW_STATE_STIPPLE_3     = (1 << 13), */ /* Not used */
+	DRW_STATE_OFFSET_POSITIVE = (1 << 12), /* Polygon offset. Does not work with lines and points. */
+	DRW_STATE_OFFSET_NEGATIVE = (1 << 13), /* Polygon offset. Does not work with lines and points. */
 	/* DRW_STATE_STIPPLE_4     = (1 << 14), */ /* Not used */
 	DRW_STATE_BLEND         = (1 << 15),
 	DRW_STATE_ADDITIVE      = (1 << 16),
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index 8eefd058719..985c4a73775 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -342,6 +342,32 @@ void drw_state_set(DRWState state)
 		}
 	}
 
+	/* Polygon Offset */
+	{
+		int test;
+		if (CHANGED_ANY_STORE_VAR(
+		        DRW_STATE_OFFSET_POSITIVE |
+		        DRW_STATE_OFFSET_NEGATIVE,
+		        test)) {
+			if (test) {
+				glEnable(GL_POLYGON_OFFSET_FILL);
+				/* Stencil Write */
+				if ((state & DRW_STATE_OFFSET_POSITIVE) != 0) {
+					glPolygonOffset(1.0f, 1.0f);
+				}
+				else if ((state & DRW_STATE_OFFSET_NEGATIVE) != 0) {
+					glPolygonOffset(-1.0f, -1.0f);
+				}
+				else {
+					BLI_assert(0);
+				}
+			}
+			else {
+				glDisable(GL_POLYGON_OFFSET_FILL);
+			}
+		}
+	}
+
 #undef CHANGED_TO
 #undef CHANGED_ANY
 #undef CHANGED_ANY_STORE_VAR