Alembic: add option to triangulate meshes upon export.

Referenced by commit 04bfea0d67, Fix T49369: Blender crashes/closes down application at alembic export of

source/blender/alembic/ABC_alembic.h

@@ -64,8 +64,12 @@ struct AlembicExportParams {
 	unsigned int face_sets : 1;
 	unsigned int use_subdiv_schema : 1;
 	unsigned int packuv : 1;
+	unsigned int triangulate : 1;
 
 	unsigned int compression_type : 1;
+
+	int quad_method;
+	int ngon_method;
 	float global_scale;
 };
 

source/blender/alembic/CMakeLists.txt

@@ -28,6 +28,7 @@ set(INC
 	../blenkernel
 	../blenlib
 	../blenloader
+	../bmesh
 	../editors/include
 	../makesdna
 	../makesrna

source/blender/alembic/intern/abc_exporter.cc

@@ -88,6 +88,9 @@ ExportSettings::ExportSettings()
     , export_ogawa(true)
     , pack_uv(false)
     , do_convert_axis(false)
+    , triangulate(false)
+    , quad_method(0)
+    , ngon_method(0)
 {}
 
 static bool object_is_smoke_sim(Object *ob)

source/blender/alembic/intern/abc_exporter.h

@@ -65,6 +65,10 @@ struct ExportSettings {
 	bool export_child_hairs;
 	bool export_ogawa;
 	bool pack_uv;
+	bool triangulate;
+
+	int quad_method;
+	int ngon_method;
 
 	bool do_convert_axis;
 	float convert_matrix[3][3];

source/blender/alembic/intern/abc_mesh.cc

@@ -37,8 +37,8 @@ extern "C" {
 #include "BLI_math_geom.h"
 #include "BLI_string.h"
 
+#include "BKE_cdderivedmesh.h"
 #include "BKE_depsgraph.h"
-#include "BKE_DerivedMesh.h"
 #include "BKE_main.h"
 #include "BKE_material.h"
 #include "BKE_mesh.h"
@@ -49,6 +49,9 @@ extern "C" {
 #include "WM_types.h"
 
 #include "ED_mesh.h"
+
+#include "bmesh.h"
+#include "bmesh_tools.h"
 }
 
 using Alembic::Abc::FloatArraySample;
@@ -538,6 +541,23 @@ DerivedMesh *AbcMeshWriter::getFinalMesh()
 		m_subsurf_mod->mode &= ~eModifierMode_DisableTemporary;
 	}
 
+	if (m_settings.triangulate) {
+		const bool tag_only = false;
+		const int quad_method = m_settings.quad_method;
+		const int ngon_method = m_settings.ngon_method;
+
+		BMesh *bm = DM_to_bmesh(dm, true);
+
+		BM_mesh_triangulate(bm, quad_method, ngon_method, tag_only, NULL, NULL, NULL);
+
+		DerivedMesh *result = CDDM_from_bmesh(bm, false);
+		BM_mesh_free(bm);
+
+		freeMesh(dm);
+
+		dm = result;
+	}
+
 	m_custom_data_config.pack_uvs = m_settings.pack_uv;
 	m_custom_data_config.mpoly = dm->getPolyArray(dm);
 	m_custom_data_config.mloop = dm->getLoopArray(dm);

source/blender/alembic/intern/alembic_capi.cc

@@ -351,6 +351,9 @@ void ABC_export(
 	job->settings.export_ogawa = (params->compression_type == ABC_ARCHIVE_OGAWA);
 	job->settings.pack_uv = params->packuv;
 	job->settings.global_scale = params->global_scale;
+	job->settings.triangulate = params->triangulate;
+	job->settings.quad_method = params->quad_method;
+	job->settings.ngon_method = params->ngon_method;
 
 	if (job->settings.frame_start > job->settings.frame_end) {
 		std::swap(job->settings.frame_start, job->settings.frame_end);

source/blender/editors/io/io_alembic.c

@@ -34,6 +34,7 @@
 #include "MEM_guardedalloc.h"
 
 #include "DNA_mesh_types.h"
+#include "DNA_modifier_types.h"
 #include "DNA_object_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_space_types.h"
@@ -121,6 +122,9 @@ static int wm_alembic_export_exec(bContext *C, wmOperator *op)
 	    .use_subdiv_schema = RNA_boolean_get(op->ptr, "subdiv_schema"),
 	    .compression_type = RNA_enum_get(op->ptr, "compression_type"),
 	    .packuv = RNA_boolean_get(op->ptr, "packuv"),
+		.triangulate = RNA_boolean_get(op->ptr, "triangulate"),
+		.quad_method = RNA_boolean_get(op->ptr, "quad_method"),
+		.ngon_method = RNA_boolean_get(op->ptr, "ngon_method"),
 
 	    .global_scale = RNA_float_get(op->ptr, "global_scale"),
 	};
@@ -212,6 +216,19 @@ static void ui_alembic_export_settings(uiLayout *layout, PointerRNA *imfptr)
 
 	row = uiLayoutRow(box, false);
 	uiItemR(row, imfptr, "apply_subdiv", 0, NULL, ICON_NONE);
+
+	row = uiLayoutRow(box, false);
+	uiItemR(row, imfptr, "triangulate", 0, NULL, ICON_NONE);
+
+	const bool triangulate = RNA_boolean_get(imfptr, "triangulate");
+
+	row = uiLayoutRow(box, false);
+	uiLayoutSetEnabled(row, triangulate);
+	uiItemR(row, imfptr, "quad_method", 0, NULL, ICON_NONE);
+
+	row = uiLayoutRow(box, false);
+	uiLayoutSetEnabled(row, triangulate);
+	uiItemR(row, imfptr, "ngon_method", 0, NULL, ICON_NONE);
 }
 
 static void wm_alembic_export_draw(bContext *UNUSED(C), wmOperator *op)
@@ -308,6 +325,15 @@ void WM_OT_alembic_export(wmOperatorType *ot)
 	RNA_def_float(ot->srna, "global_scale", 1.0f, 0.0001f, 1000.0f, "Scale",
 	              "Value by which to enlarge or shrink the objects with respect to the world's origin",
 	              0.0001f, 1000.0f);
+
+	RNA_def_boolean(ot->srna, "triangulate", false, "Triangulate",
+	                "Export Polygons (Quads & NGons) as Triangles");
+
+	RNA_def_enum(ot->srna, "quad_method", rna_enum_modifier_triangulate_quad_method_items,
+	             MOD_TRIANGULATE_QUAD_SHORTEDGE, "Quad Method", "Method for splitting the quads into triangles");
+
+	RNA_def_enum(ot->srna, "ngon_method", rna_enum_modifier_triangulate_quad_method_items,
+	             MOD_TRIANGULATE_NGON_BEAUTY, "Polygon Method", "Method for splitting the polygons into triangles");
 }
 
 /* ************************************************************************** */

source/blender/makesrna/intern/rna_scene_api.c

@@ -210,7 +210,10 @@ static void rna_Scene_alembic_export(
         int use_subdiv_schema,
         int compression_type,
         int packuv,
-        float scale)
+        float scale,
+        int triangulate,
+        int quad_method,
+        int ngon_method)
 {
 /* We have to enable allow_threads, because we may change scene frame number
  * during export. */
@@ -240,6 +243,9 @@ static void rna_Scene_alembic_export(
 	    .use_subdiv_schema = use_subdiv_schema,
 	    .compression_type = compression_type,
 	    .packuv = packuv,
+		.triangulate = triangulate,
+		.quad_method = quad_method,
+		.ngon_method = ngon_method,
 
 	    .global_scale = scale,
 	};
@@ -404,6 +410,9 @@ void RNA_api_scene(StructRNA *srna)
 	RNA_def_enum(func, "compression_type", rna_enum_abc_compression_items, 0, "Compression", "");
 	RNA_def_boolean(func, "packuv"		, 0, "Export with packed UV islands", "Export with packed UV islands");
 	RNA_def_float(func, "scale", 1.0f, 0.0001f, 1000.0f, "Scale", "Value by which to enlarge or shrink the objects with respect to the world's origin", 0.0001f, 1000.0f);
+	RNA_def_boolean(func, "triangulate", 0, "Triangulate", "Export Polygons (Quads & NGons) as Triangles");
+	RNA_def_enum(func, "quad_method", rna_enum_modifier_triangulate_quad_method_items, 0, "Quad Method", "Method for splitting the quads into triangles");
+	RNA_def_enum(func, "ngon_method", rna_enum_modifier_triangulate_quad_method_items, 0, "Polygon Method", "Method for splitting the polygons into triangles");
 
 	RNA_def_function_flag(func, FUNC_USE_CONTEXT);
 #endif