From 15a15ae2502784e32ff5d043b4713c967c5be701 Mon Sep 17 00:00:00 2001
From: bobarna <barnabas.borcsok@gmail.com>
Date: Sat, 4 Apr 2020 16:39:41 +0200
Subject: [PATCH] first iteration (not working) ear cutting
---
sirius.cpp | 125 +++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 101 insertions(+), 24 deletions(-)
diff --git a/sirius.cpp b/sirius.cpp
index 516c815..9ea5f62 100644
--- a/sirius.cpp
+++ b/sirius.cpp
@@ -121,12 +121,9 @@ public:
};
class BaseCircle : public Drawable {
- BaseCircle() = default;
public:
- static BaseCircle generate() {
- BaseCircle baseCircle;
- std::vector<vec2> &vertices = baseCircle.vertices;
+ BaseCircle() {
// calculate all the vertices of the base circle:
float step = 360.0 / BASE_CIRCLE_SEGMENTS;
float currAngle = 0;
@@ -144,11 +141,10 @@ public:
currAngle += step;
vertices.emplace_back(cos(degToRad(currAngle)), sin(degToRad(currAngle)));
}
-
- return baseCircle;
}
void draw() override {
+ init();
glBindVertexArray(vao); // Draw call
glDrawArrays(GL_TRIANGLES, 0, vertices.size());
}
@@ -198,20 +194,95 @@ public:
printf("%f %f\n", cx, cy);
c = vec2(cx, cy);
r = sqrtf((c.x - p1.x) * (c.x - p1.x) + (c.y - p1.y) * (c.y - p1.y));
+ }
-// init();
+};
+inline float lengthv2(vec2 v) {
+ return sqrt(v.x * v.x + v.y * v.y);
+}
+
+inline float crossv2(vec2 a, vec2 b) {
+ return a.x * b.y - a.y * b.x;
+}
+
+inline bool intersectEachOther(vec2 p1, vec2 p2, vec2 q1, vec2 q2) {
+ return
+ lengthv2(crossv2(q1 - q2, p1 - q1)) * lengthv2(crossv2(q1 - q2, p2 - q1)) < 0 &&
+ lengthv2(crossv2(q1 - q2, p1 - q1)) * lengthv2(crossv2(q1 - q2, p2 - q1)) < 0;
+}
+
+class Triangulated : public Drawable {
+ std::vector<vec2> remainingVertices;
+
+public:
+ explicit Triangulated(std::vector<vec2> points) {
+ remainingVertices = points;
+ vertices.reserve(remainingVertices.size() * 3);
+ triangulate();
+ };
+
+ void triangulate() {
+ while (!remainingVertices.empty()) {
+ //finding an ear
+ auto currVertex = remainingVertices.begin();
+ //check if current vertex is an ear
+ vec2 currPotDiag1 = *getNextVertex(currVertex);
+ vec2 currPotDiag2 = *getPreviousVertex(currVertex);
+
+ //check if current potential diagonal intersects any edges
+ // skipping edges that share a vertex with it
+
+ for (auto currEdgeStart = getPreviousVertex(getPreviousVertex(currVertex));
+ currEdgeStart != getNextVertex(getNextVertex(currVertex)); currEdgeStart = getPreviousVertex(currEdgeStart))
+ if (intersectEachOther(vec2(currEdgeStart->x, currEdgeStart->y),
+ vec2(getNextVertex(currEdgeStart)->x, getNextVertex(currEdgeStart)->y),
+ currPotDiag1, currPotDiag2))
+ break;
+
+ //check if current potential diagonal is fully outside the polygon
+ vec2 infinity(250, 250);
+ vec2 middle((currPotDiag1 + currPotDiag2)/2);
+ int numberOfIntersections = 0;
+ for(auto currEdgeStart = remainingVertices.begin(); currEdgeStart != remainingVertices.begin(); currEdgeStart = getPreviousVertex(currEdgeStart))
+ if(intersectEachOther(currEdgeStart->x, *getNextVertex(currEdgeStart), infinity, middle))
+ numberOfIntersections++;
+ if(numberOfIntersections%2 == 0)
+ break; // the potential diagonal is fully outside, it's not an ear.
+
+ //it's an ear!
+ vertices.emplace_back(*currVertex);
+ vertices.emplace_back(currPotDiag1);
+ vertices.emplace_back(currPotDiag2);
+
+ remainingVertices.erase(currVertex);
+ }
}
-// void draw() override {
-// glBindVertexArray(vao); // Draw call
-// setColor(vec3(1, 0, 0));
-// glDrawArrays(GL_LINE_LOOP, 0, vertices.size());
-// }
+ std::vector<vec2>::iterator getPreviousVertex(std::vector<vec2>::iterator currVertex) {
+ if (currVertex == remainingVertices.begin())
+ return remainingVertices.end();
+ else
+ return --currVertex;
+ }
+
+ std::vector<vec2>::iterator getNextVertex(std::vector<vec2>::iterator currVertex) {
+ if (currVertex == remainingVertices.end())
+ return remainingVertices.begin();
+ else
+ return ++currVertex;
+ };
+
+ void draw() override {
+ init();
+ glBindVertexArray(vao); // Draw call
+ glDrawArrays(GL_TRIANGLES, 0, vertices.size());
+ }
};
class SiriusTriangle : public Drawable {
std::vector<Point> points;
+ std::vector<Triangulated> triangulated;
public:
int n = 0;
@@ -224,8 +295,11 @@ public:
if (n > 3) printf("Can't add 4th point to a triangle!\n");
printf("%d\n", n);
if (n == 2) generateLineSegment(points[0], points[1]);
- if (n == 3) generateLineSegment(points[2], points[0]);
- if (n == 3) generateLineSegment(points[1], points[2]);
+ if (n == 3) {
+ generateLineSegment(points[2], points[0]);
+ generateLineSegment(points[1], points[2]);
+ triangulated.emplace_back(Triangulated(vertices));
+ }
}
@@ -270,16 +344,22 @@ public:
}
void draw() override {
- for (auto &point: points)
- point.draw();
+ //filling out the triangulated area
+ if(n == 3)
+ triangulated[0].draw();
+
//Time to draw the edges
if (n == 3) {
init();
glBindVertexArray(vao); // Draw call
- setColor(vec3(1, 0, 0));
+ setColor(vec3(0.6, 0.2, 0.6));
glDrawArrays(GL_LINE_LOOP, 0, vertices.size());
}
+
+
+ for (auto &point: points)
+ point.draw();
}
};
@@ -305,7 +385,7 @@ public:
}
};
-BaseCircle baseCircle = BaseCircle::generate();
+BaseCircle baseCircle = BaseCircle();
SiriusTriangleManager siriusTriangleManager = SiriusTriangleManager();
// Initialization, create an OpenGL context
@@ -314,7 +394,7 @@ void onInitialization() {
baseCircle.init();
siriusTriangleManager.addPoint(vec2(-0.6, 0.4));
- siriusTriangleManager.addPoint(vec2(-0.8, 0.2));
+ siriusTriangleManager.addPoint(vec2(-0.8, -0.2));
siriusTriangleManager.addPoint(vec2(-0.2, -0.6));
// create program for the GPU
@@ -383,11 +463,6 @@ void onMouse(int button, int state, int pX,
break;
}
-// siriusTriangleManager.addPoint(vec2(-.8f, -.4f));
-// siriusTriangleManager.addPoint(vec2(-.2f, -.6f));
-// siriusTriangleManager.addPoint(vec2(-.4f, .4f));
-// siriusTriangleManager.draw();
-
if (state == GLUT_DOWN && button == GLUT_LEFT_BUTTON) {
siriusTriangleManager.addPoint(vec2(cX, cY));
siriusTriangleManager.draw();
@@ -399,3 +474,5 @@ void onMouse(int button, int state, int pX,
void onIdle() {
long time = glutGet(GLUT_ELAPSED_TIME); // elapsed time since the start of the program
}
+
+#include <utility>
--
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