DRW: Culling: Expose & Add culling functions to engines.

This way engines can do preemptive culling by themselves.

source/blender/draw/intern/DRW_render.h

@@ -77,6 +77,11 @@ typedef struct DRWInterface DRWInterface;
 typedef struct DRWPass DRWPass;
 typedef struct DRWShadingGroup DRWShadingGroup;
 
+/* TODO Put it somewhere else? */
+typedef struct BoundSphere {
+	float center[3], radius;
+} BoundSphere;
+
 /* declare members as empty (unused) */
 typedef char DRWViewportEmptyList;
 
@@ -478,6 +483,10 @@ void DRW_state_invert_facing(void);
 void DRW_state_clip_planes_add(float plane_eq[4]);
 void DRW_state_clip_planes_reset(void);
 
+/* Culling, return true if object is inside view frustum. */
+bool DRW_culling_sphere_test(BoundSphere *bsphere);
+bool DRW_culling_box_test(BoundBox *bbox);
+
 /* Selection */
 void DRW_select_load_id(unsigned int id);
 

source/blender/draw/intern/draw_manager.c

@@ -465,6 +465,7 @@ void DRW_viewport_matrix_override_set(float mat[4][4], DRWViewportMatrixType typ
 	copy_m4_m4(DST.view_data.matstate.mat[type], mat);
 	DST.override_mat |= (1 << type);
 	DST.dirty_mat = true;
+	DST.clipping.updated = false;
 }
 
 void DRW_viewport_matrix_override_unset(DRWViewportMatrixType type)
@@ -473,6 +474,7 @@ void DRW_viewport_matrix_override_unset(DRWViewportMatrixType type)
 	copy_m4_m4(DST.view_data.matstate.mat[type], DST.original_mat.mat[type]);
 	DST.override_mat &= ~(1 << type);
 	DST.dirty_mat = true;
+	DST.clipping.updated = false;
 }
 
 void DRW_viewport_matrix_override_set_all(DRWMatrixState *state)
@@ -480,6 +482,7 @@ void DRW_viewport_matrix_override_set_all(DRWMatrixState *state)
 	memcpy(DST.view_data.matstate.mat, state, sizeof(DRWMatrixState));
 	DST.override_mat = 0xFFFFFF;
 	DST.dirty_mat = true;
+	DST.clipping.updated = false;
 }
 
 void DRW_viewport_matrix_override_unset_all(void)
@@ -487,6 +490,7 @@ void DRW_viewport_matrix_override_unset_all(void)
 	memcpy(DST.view_data.matstate.mat, DST.original_mat.mat, sizeof(DRWMatrixState));
 	DST.override_mat = 0;
 	DST.dirty_mat = true;
+	DST.clipping.updated = false;
 }
 
 bool DRW_viewport_is_persp_get(void)

source/blender/draw/intern/draw_manager.h

@@ -76,12 +76,6 @@
 
 #endif  /* USE_PROFILE */
 
-/* TODO Put it somewhere else? */
-typedef struct BoundSphere {
-	float center[3], radius;
-} BoundSphere;
-
-
 /* ------------ Data Structure --------------- */
 /**
  * Data structure containing all drawcalls organized by passes and materials.

source/blender/draw/intern/draw_manager_exec.c

@@ -530,11 +530,15 @@ static void draw_clipping_setup_from_view(void)
 		/* Transform to world space. */
 		mul_m4_v3(viewinv, bsphere->center);
 	}
+
+	DST.clipping.updated = true;
 }
 
 /* Return True if the given BoundSphere intersect the current view frustum */
-static bool draw_culling_sphere_test(BoundSphere *bsphere)
+bool DRW_culling_sphere_test(BoundSphere *bsphere)
 {
+	draw_clipping_setup_from_view();
+
 	/* Bypass test if radius is negative. */
 	if (bsphere->radius < 0.0f)
 		return true;
@@ -556,6 +560,32 @@ static bool draw_culling_sphere_test(BoundSphere *bsphere)
 	return true;
 }
 
+/* Return True if the given BoundBox intersect the current view frustum.
+ * bbox must be in world space. */
+bool DRW_culling_box_test(BoundBox *bbox)
+{
+	draw_clipping_setup_from_view();
+
+	/* 6 view frustum planes */
+	for (int p = 0; p < 6; p++) {
+		/* 8 box vertices. */
+		for (int v = 0; v < 8 ; v++) {
+			float dist = plane_point_side_v3(DST.clipping.frustum_planes[p], bbox->vec[v]);
+			if (dist > 0.0f) {
+				/* At least one point in front of this plane.
+				 * Go to next plane. */
+				break;
+			}
+			else if (v == 7) {
+				/* 8 points behind this plane. */
+				return false;
+			}
+		}
+	}
+
+	return true;
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
@@ -572,7 +602,7 @@ static void draw_matrices_model_prepare(DRWCallState *st)
 		st->cache_id = DST.state_cache_id;
 	}
 
-	if (draw_culling_sphere_test(&st->bsphere)) {
+	if (DRW_culling_sphere_test(&st->bsphere)) {
 		st->flag &= ~DRW_CALL_CULLED;
 	}
 	else {
@@ -934,8 +964,6 @@ static void drw_draw_pass_ex(DRWPass *pass, DRWShadingGroup *start_group, DRWSha
 			}
 		}
 
-		DST.clipping.updated = false;
-
 		/* TODO dispatch threads to compute matrices/culling */
 	}