Implement simple hole stencil to resolve holes in GDS polygons.

.gitmodules

@@ -6,3 +6,6 @@
 	path = 3rdparty/libfort
 	url = https://git.shimatta.de/3rd-party/libfort
 	branch = develop
+[submodule "3rdparty/poly2tri"]
+	path = 3rdparty/poly2tri
+	url = https://git.shimatta.de/3rd-party/poly2tri.git

CMakeLists.txt

@@ -2,7 +2,7 @@ if (POLICY CMP0048)
   cmake_policy(SET CMP0048 NEW)
 endif (POLICY CMP0048)
 
-project(gds-render LANGUAGES C)
+project(gds-render LANGUAGES C CXX)
 
 if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
   set(CMAKE_INSTALL_PREFIX "/usr/" CACHE PATH "..." FORCE)
@@ -75,8 +75,6 @@ SET_SOURCE_FILES_PROPERTIES(${SOURCE_GENERATED} PROPERTIES GENERATED 1)
 
 add_subdirectory(test)
 
-add_compile_options(-Wall -Wextra -Wold-style-declaration -Wuninitialized -Wmaybe-uninitialized -Wunused-parameter)
-
 add_subdirectory(resources)
 add_subdirectory(doxygen)
 add_subdirectory(translations)
@@ -91,6 +89,8 @@ if(OPENGL_PREVIEW)
 	add_subdirectory(preview-rendering)
 endif(OPENGL_PREVIEW)
 
+add_compile_options(-Wall -Wextra -Wold-style-declaration -Wuninitialized -Wmaybe-uninitialized -Wunused-parameter)
+
 link_directories(${GLIB_LINK_DIRS} ${GTK3_LINK_DIRS} ${CAIRO_LINK_DIRS})
 add_definitions(${GLIB2_CFLAGS_OTHER})
 

preview-rendering/CMakeLists.txt

@@ -8,8 +8,11 @@ pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
 
 aux_source_directory("src" SRCS)
 
+add_subdirectory(poly2tri-wrapper)
+
 add_library(${PROJECT_NAME} STATIC ${SRCS})
 target_include_directories(${PROJECT_NAME} PUBLIC "include")
 target_include_directories(${PROJECT_NAME} PRIVATE ${EPOXY_INCLUDE_DIRS} ${GLIB_INCLUDE_DIRS} ${GTK3_INCLUDE_DIRS})
 target_link_directories(${PROJECT_NAME} PUBLIC ${EPOXY_LINK_DIRS} ${GLIB_LINK_DIRS} ${GTK3_LINK_DIRS})
-target_link_libraries(${PROJECT_NAME} ${GLIB_LDFLAGS} ${EPOXY_LDFLAGS} ${GTK3_LDFLAGS})
+target_link_libraries(${PROJECT_NAME} ${GLIB_LDFLAGS} ${EPOXY_LDFLAGS} ${GTK3_LDFLAGS} poly2tri-wrapper)
+

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

@@ -0,0 +1,16 @@
+#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 +1,132 @@
+#include <iostream>
+#include <poly2tri/poly2tri.h>
+#include <poly2tri-wrapper/poly2tri-wrapper.h>
+//#include <gds-render/gds-utils/gds-types.h>
+#include <vector>
+
+class Hole {
+private:
+	std::vector <p2t::Point *> hole_vertices;
+public:
+	const std::vector <p2t::Point *> &get_vertices()
+	{
+		return hole_vertices;
+	}
+
+	void add_vertex(const p2t::Point &point)
+	{
+		auto pt = new p2t::Point(point);
+		hole_vertices.push_back(pt);
+	}
+
+	Hole(std::vector<p2t::Point *>::iterator start, std::vector<p2t::Point *>::iterator end)
+	{
+		hole_vertices = std::vector<p2t::Point *>(start, end);
+	}
+
+};
+
+
+static std::vector<Hole> resolve_holes_in_polyline(std::vector<p2t::Point *> &polyline)
+{
+	bool found = false;
+	std::vector<Hole> holes;
+	std::vector<std::pair<
+			std::vector<p2t::Point *>::iterator,
+			std::vector<p2t::Point *>::iterator>
+			> points_to_remove;
+
+	for (auto start_it = polyline.begin(); start_it != polyline.end(); start_it++) {
+		for (auto check_it = std::next(start_it); check_it != polyline.end(); check_it++) {
+			/* Check if points are equal */
+			if (**start_it == **check_it) {
+				if (**std::prev(check_it) == **std::next(start_it)) {
+					/* Found a hole. Everything between start_it and check_it can be removed */
+					auto hole = Hole(std::next(start_it)+1, check_it);
+					holes.push_back(hole);
+					auto tbd = std::make_pair(start_it, check_it);
+					points_to_remove.push_back(tbd);
+					found = true;
+					break;
+				}
+			}
+		}
+		if (found)
+			break;
+	}
+
+	/* Remove form polyline */
+	for (auto it_pair_it = points_to_remove.begin(); it_pair_it != points_to_remove.end(); it_pair_it++) {
+		auto it_pair = *it_pair_it;
+		delete *it_pair.first;
+		delete *std::next(it_pair.first);
+		polyline.erase(it_pair.first, it_pair.second);
+	}
+
+	if (found) {
+		auto new_holes = resolve_holes_in_polyline(polyline);
+		holes.insert(holes.end(), new_holes.begin(), new_holes.end());
+	}
+
+
+	return holes;
+}
+
+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 holes = resolve_holes_in_polyline(polyline);
+
+	auto my_cdt = p2t::CDT(polyline);
+
+	for (auto hole_it = holes.begin(); hole_it != holes.end(); hole_it++) {
+		my_cdt.AddHole((*hole_it).get_vertices());
+	}
+
+	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;
+}

preview-rendering/src/preview-rendering-gui.c

@@ -1,4 +1,5 @@
 #include <preview-rendering/preview-rendering-gui.h>
+#include <poly2tri-wrapper/poly2tri-wrapper.h>
 #include <epoxy/gl.h>
 
 struct _OpenGlPreviewGui {
@@ -7,8 +8,10 @@ struct _OpenGlPreviewGui {
 	GtkGLArea *gl_area;
 	unsigned int polygon_shader_prog;
 	unsigned int vao;
+	unsigned int vao_vertex_count;
 	unsigned int vbo;
 	float color[4];
+	gboolean line;
 };
 
 G_DEFINE_TYPE(OpenGlPreviewGui, opengl_preview_gui, G_TYPE_OBJECT)
@@ -47,12 +50,12 @@ static gboolean gl_area_render(GtkGLArea *area, GdkGLContext *context, gpointer
 
 	glClearColor (0, 0, 0, 1.0);
 	glClear (GL_COLOR_BUFFER_BIT);
-	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+	glPolygonMode(GL_FRONT_AND_BACK, gui->line ? GL_LINE : GL_FILL);
 	glUseProgram(gui->polygon_shader_prog);
 	glBindVertexArray(gui->vao);
 	loc = glGetUniformLocation(gui->polygon_shader_prog, "const_color");
 	glUniform4fv(loc, 1, gui->color);
-	glDrawArrays(GL_TRIANGLES, 0, 3);
+	glDrawArrays(GL_TRIANGLES, 0, gui->vao_vertex_count);
 
 	glFlush();
 
@@ -78,6 +81,7 @@ static int compile_shader_from_resource(GLenum shader_type, const char *res_name
 	g_bytes_unref(res_bytes);
 	if (shader)
 		*shader = sh;
+
 	return success;
 }
 
@@ -90,6 +94,9 @@ static gboolean gl_area_realize(GtkGLArea *area, gpointer user)
 	unsigned int vao;
 	OpenGlPreviewGui *gui;
 	int success;
+	struct gds_graphics gfx;
+	struct gds_point points[20];
+	size_t vertex_count;
 
 	gui = GDS_RENDER_OPENGL_PREVIEW_GUI(user);
 
@@ -120,30 +127,111 @@ static gboolean gl_area_realize(GtkGLArea *area, gpointer user)
 	glDeleteShader(fs);
 
 
-	float vertices[] = {
-		-0.5f, -0.5f,
-		0.5f, -0.5f,
-		0.0f, 0.5f,
-	};
+
+
+
+
+	gui->polygon_shader_prog = prog;
+
+
+	gfx.vertices = NULL;
+	points[0].x = -100;
+	points[0].y = -100;
+
+	points[1].x = -100;
+	points[1].y = +100;
+
+	points[2].x = +0;
+	points[2].y = +100;
+
+	points[3].x = +0;
+	points[3].y = 20;
+
+	points[4].x = -20;
+	points[4].y = 20;
+
+	points[5].x = -20;
+	points[5].y = -20;
+
+	points[6].x = 20;
+	points[6].y = -20;
+
+	points[7].x = 20;
+	points[7].y = 20;
+
+	points[8].x = 0;
+	points[8].y = 20;
+
+	points[9].x = 0;
+	points[9].y = 100;
+
+	points[10].x = 100;
+	points[10].y = 100;
+
+
+	points[11].x = 100;
+	points[11].y = 5;
+
+	points[12].x = 60;
+	points[12].y = 5;
+
+	points[13].x = 60;
+	points[13].y = 20;
+
+	points[14].x = 50;
+	points[14].y = 20;
+
+	points[15].x = 50;
+	points[15].y = 0;
+
+	points[16].x = 60;
+	points[16].y = 0;
+
+	points[17].x = 60;
+	points[17].y = 5;
+
+	points[18].x = 100;
+	points[18].y = 5;
+
+
+	points[19].x = 100;
+	points[19].y = -100;
+
+	gfx.gfx_type = GRAPHIC_POLYGON;
+
+	for (int i = 0; i < 20; i++) {
+		gfx.vertices = g_list_append(gfx.vertices, &points[i]);
+	}
+
+	float *vertices = NULL;
+
+	tesselator_triangulate_polygon(&gfx, 180.0, &vertices, &vertex_count);
+	gui->vao_vertex_count = vertex_count;
 
 	glGenVertexArrays(1, &vao);
 	glBindVertexArray(vao);
 	glGenBuffers(1, &vbo);
 	glBindBuffer(GL_ARRAY_BUFFER, vbo);
-	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+	glBufferData(GL_ARRAY_BUFFER, vertex_count*2*sizeof(float), vertices, GL_STATIC_DRAW);
 	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2*sizeof(float), (void *)0);
 	glEnableVertexAttribArray(0);
 
+	free(vertices);
 
-
-	gui->polygon_shader_prog = prog;
 	gui->vao = vao;
 	gui->vbo = vbo;
 
+	g_list_free(gfx.vertices);
+
 	return TRUE;
 
 }
 
+static void on_clicked(GtkWidget *sender, gboolean *p)
+{
+	*p = !*p;
+}
+
 static void opengl_preview_gui_init(OpenGlPreviewGui *self)
 {
 	GtkBuilder *builder;
@@ -153,6 +241,9 @@ static void opengl_preview_gui_init(OpenGlPreviewGui *self)
 	self->gl_area = GTK_GL_AREA(gtk_builder_get_object(builder, "gl-area"));
 	g_signal_connect(self->gl_area, "render", G_CALLBACK(gl_area_render), self);
 	g_signal_connect(self->gl_area, "realize", G_CALLBACK(gl_area_realize), self);
+
+	g_signal_connect(gtk_builder_get_object(builder, "test-button"), "clicked", G_CALLBACK(on_clicked), &self->line);
+	self->line = FALSE;
 	g_object_ref(self->gl_area);
 }
 

resources/preview-window.glade

@@ -12,7 +12,7 @@
         <property name="can-focus">False</property>
         <property name="baseline-position">bottom</property>
         <child>
-          <object class="GtkButton">
+          <object class="GtkButton" id="test-button">
             <property name="label" translatable="yes">button</property>
             <property name="visible">True</property>
             <property name="can-focus">True</property>