Add poly2tri and C++ wrapper for polygon tesselation.

preview-rendering/poly2tri-wrapper/CMakeLists.txt

@@ -0,0 +1,11 @@
+project(poly2tri-wrapper LANGUAGES CXX)
+cmake_minimum_required(VERSION 3.12)
+
+add_subdirectory(../../3rdparty/poly2tri poly2tri)
+set(CMAKE_CXX_STANDARD 14)
+
+aux_source_directory("src" WRAPPER_SOURCES)
+
+add_library(${PROJECT_NAME} STATIC ${WRAPPER_SOURCES})
+target_link_libraries(${PROJECT_NAME} poly2tri)
+target_include_directories(${PROJECT_NAME} PUBLIC "include")

preview-rendering/poly2tri-wrapper/include/poly2tri-wrapper/poly2tri-wrapper.h

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+#ifndef _POLY2TRI_WRAPPER_H_
+#define _POLY2TRI_WRAPPER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <gds-render/gds-utils/gds-types.h>
+
+int tesselator_triangulate_polygon(const struct gds_graphics *gfx, double scale, float **output_vertices, size_t *vertex_count);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* _POLY2TRI_WRAPPER_H_ */

preview-rendering/poly2tri-wrapper/src/poly2tri-wrapper.cpp

@@ -0,0 +1,58 @@
+#include <iostream>
+#include <poly2tri/poly2tri.h>
+#include <poly2tri-wrapper/poly2tri-wrapper.h>
+//#include <gds-render/gds-utils/gds-types.h>
+#include <vector>
+
+int tesselator_triangulate_polygon(const struct gds_graphics *gfx, double scale, float** output_vertices, size_t *vertex_count)
+{
+	GList *vertex_iter;
+	std::vector<p2t::Point*> polyline;
+
+	if (gfx->gfx_type != GRAPHIC_POLYGON)
+		return -1;
+
+	for (vertex_iter = gfx->vertices; vertex_iter; vertex_iter = g_list_next(vertex_iter)) {
+		struct gds_point *gds_pt = (struct gds_point *)vertex_iter->data;
+		auto pt = new p2t::Point((double)gds_pt->x/scale, (double)gds_pt->y/scale);
+		polyline.push_back(pt);
+	}
+
+	auto my_cdt = p2t::CDT(polyline);
+
+	my_cdt.Triangulate();
+
+	auto triangles = my_cdt.GetTriangles();
+
+
+
+	/* Free the triangles */
+	for (auto it = triangles.begin(); it != triangles.end(); it++) {
+		auto triangle = *it;
+		std::cout << "Triangle: " <<
+			     triangle->GetPoint(0)->x << "|" << triangle->GetPoint(0)->y << ","
+			  << triangle->GetPoint(1)->x << "|" << triangle->GetPoint(1)->x << ","
+			  << triangle->GetPoint(2)->x << "|" << triangle->GetPoint(2)->y
+			  << std::endl;
+	}
+
+	/* Get the amount of triangles */
+	auto count = triangles.size();
+	*output_vertices = (float *)malloc(2*sizeof(float)*3*count);
+
+	*vertex_count = count * 3;
+	/* Free the points in the vector */
+	for (unsigned int i = 0; i < count; i++) {
+		for (int j = 0; j < 3; j++) {
+			auto pt = triangles[i]->GetPoint(j);
+			unsigned int idx = i * 6 + j * 2;
+			(*output_vertices)[idx] = (float)pt->x;
+			(*output_vertices)[idx + 1] = (float)pt->y;
+		}
+	}
+
+	for (auto it = polyline.begin(); it != polyline.end(); it++)
+		delete *it;
+
+	return 0;
+}