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can draw sdf
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@iamyoukou
iamyoukou committed Oct 8, 2019
1 parent d99fbda commit dc5553c
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Showing 7 changed files with 231 additions and 148 deletions.
9 changes: 9 additions & 0 deletions src/constants.h
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@@ -1,6 +1,9 @@
#pragma once

#include "algebra.h"
#include <glm/glm.hpp>
#include <glm/gtx/compatibility.hpp>
#include <glm/gtx/string_cast.hpp>

/* -----------------------------------------------------------------------
| OPTIONS
Expand Down Expand Up @@ -32,6 +35,12 @@ const static float DT = 0.0005f; // Time-step
/* ----- GRID ----- */
const static float H_INV = 1.0f; // cell size ?

/* for sdf */
const static glm::vec2 worldOrigin(0.f, 0.f);
const static float sdfCellSize = H_INV;
const static int sdfWidth = X_GRID;
const static int sdfHeight = Y_GRID;

/* ----- TRANSFER ----- */
#if INTERPOLATION == 1
const static int CUB = 2;
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Binary file modified src/main
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97 changes: 70 additions & 27 deletions src/main.cpp
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Expand Up @@ -9,6 +9,7 @@
/* Declarations */
void initGLContext();
GLFWwindow *initGLFWContext();
void drawSdf(GLFWwindow *);
Solver *Simulation;
int t_count = 0;
int frameNumber = 0;
Expand Down Expand Up @@ -36,9 +37,9 @@ void Initialization() {
std::vector<Material> inParticles = Material::InitializeParticles();
std::vector<Polygon> inPolygons = Polygon::InitializePolygons();

// std::cout << inPolygons.size() << '\n';

Simulation = new Solver(inBorders, inNodes, inParticles, inPolygons);

Simulation->computeSdf(); // for static objects, compute only once
}

void Update() {
Expand Down Expand Up @@ -86,10 +87,11 @@ int main(int argc, char **argv) {

#else
/* [2] : show result on OpenGL window, and record an .mp4 if selected */
const int frameLimit = 3;
const int frameLimit = 99999;

GLFWwindow *window = initGLFWContext();
initGLContext();

while (!glfwWindowShouldClose(window) && frameNumber < frameLimit) {

glClear(GL_COLOR_BUFFER_BIT);
Expand All @@ -99,42 +101,47 @@ int main(int argc, char **argv) {
// AddParticles();

// P2G, compute grid forces, etc.
Update();
// Update();

// Display frame at desired rate
if (t_count % (int)(DT_render / DT) == 0) {
Simulation->Draw();
glfwSwapBuffers(window);

#if RECORD_VIDEO
std::string dir = "../result/sim";

// zero padding
std::string num = std::to_string(frameNumber);
num = std::string(4 - num.length(), '0') + num;
std::string output = dir + num + ".png";
// for testing sdf
drawSdf(window);

// use opencv to save a frame
// the frame size becomes twice from frame 2,
// thus multiplying 2 is needed.
// don't know why
cv::Mat outImg(Y_WINDOW * 2, X_WINDOW * 2, CV_8UC3);
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(0, 0, X_WINDOW * 2, Y_WINDOW * 2, GL_BGR, GL_UNSIGNED_BYTE,
(GLvoid *)outImg.data);
cv::flip(outImg, outImg, 0);
cv::imwrite(output, outImg);

std::cout << "Frame " << frameNumber << " saved." << '\n';
glfwSwapBuffers(window);

frameNumber++;
#endif
// #if RECORD_VIDEO
// std::string dir = "../result/sim";
//
// // zero padding
// std::string num = std::to_string(frameNumber);
// num = std::string(4 - num.length(), '0') + num;
// std::string output = dir + num + ".png";
//
// // use opencv to save a frame
// // the frame size becomes twice from frame 2,
// // thus multiplying 2 is needed.
// // don't know why
// cv::Mat outImg(Y_WINDOW * 2, X_WINDOW * 2, CV_8UC3);
// glPixelStorei(GL_PACK_ALIGNMENT, 4);
// glReadPixels(0, 0, X_WINDOW * 2, Y_WINDOW * 2, GL_BGR,
// GL_UNSIGNED_BYTE,
// (GLvoid *)outImg.data);
// cv::flip(outImg, outImg, 0);
// cv::imwrite(output, outImg);
//
// std::cout << "Frame " << frameNumber << " saved." << '\n';
//
// frameNumber++;
// #endif

glfwPollEvents();
} // end outer if

// Don't forget to reset grid every frame !!
Simulation->ResetGrid();
// Simulation->ResetGrid();

t_count++;
} // end while
Expand Down Expand Up @@ -187,3 +194,39 @@ void initGLContext() {
glClearColor(.659f, .694f, .82f, .0f);
glClear(GL_COLOR_BUFFER_BIT);
}

// for testing sdf
void drawSdf(GLFWwindow *wnd) {
double xpos, ypos;
glfwGetCursorPos(wnd, &xpos, &ypos);

float fx, fy;
fx = xpos / (float)X_WINDOW;
fy = ypos / (float)Y_WINDOW;

// Note: (0, 0) is at right-bottom
float wx, wy;
wx = fx * X_GRID;
wy = (1.f - fy) * Y_GRID;

// for test
// draw sdf gradient at a given point
glm::vec2 start = glm::vec2(wx, wy);
float dist = Simulation->getDistance(start);
glm::vec2 grad = Simulation->getGradient(start);
glm::vec2 end = start + dist * grad;

// start.x = start.x / (float)X_GRID * (float)X_WINDOW;
// start.y = start.y / (float)Y_GRID * (float)Y_WINDOW;
//
// end.x = end.x / (float)X_GRID * (float)X_WINDOW;
// end.y = end.y / (float)Y_GRID * (float)Y_WINDOW;

glLineWidth(4);
glColor3f(1.f, 0.f, 0.f);

glBegin(GL_LINES);
glVertex2f(start.x, start.y); // start point
glVertex2f(end.x, end.y); // end point
glEnd();
}
115 changes: 0 additions & 115 deletions src/sdf.cpp
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Original file line number Diff line number Diff line change
@@ -1,8 +1,6 @@
#include "sdf.h"
#include "solver.h"

glm::vec2 worldOrigin(0.f, 0.f);

/* Functions in class Polygon */
void Polygon::computeAabb() {
lb = vertices[0];
Expand Down Expand Up @@ -97,116 +95,3 @@ void Polygon::DrawPolygon() {
glEnd();
}
/* end Functions in class Polygon */

bool intersect(glm::vec2 p1, glm::vec2 p2, glm::vec2 p3, glm::vec2 p4) {
glm::vec3 a(p1, 0), b(p2, 0), c(p3, 0), d(p4, 0);

float crossAcAb, crossAbAd, crossDaDc, crossDcDb;
crossAcAb = glm::cross(c - a, b - a).z;
crossAbAd = glm::cross(b - a, d - a).z;
crossDaDc = glm::cross(a - d, c - d).z;
crossDcDb = glm::cross(c - d, b - d).z;

if (crossAcAb * crossAbAd > 0 && crossDaDc * crossDcDb > 0) {
return true;
} else {
return false;
}
}

bool inside_polygon(glm::vec2 p, Polygon &poly) {
int count = 0;
glm::vec2 q(1234567.f, 1234567.f); // a point at the infinity
int len = poly.vertices.size();

for (int i = 0; i < len; i++) {
glm::vec2 &start = poly.vertices[i];
glm::vec2 &end = poly.vertices[(i + 1) % len];
count += intersect(p, q, start, end);
}

return count % 2 == 1;
}

float nearest_distance(glm::vec2 p, Polygon &poly) {
float dist = 9999.f;
int len = poly.vertices.size();

for (int i = 0; i < len; i++) {
glm::vec2 &a = poly.vertices[i];
glm::vec2 &b = poly.vertices[(i + 1) % len];

//当前处理的边定义为 ab
glm::vec2 ab = b - a;
float abLength = glm::length(ab);
glm::vec2 dir = glm::normalize(ab);

//求点 p 在边 ab 上的投影点 q
//于是，线段 pq 的长度就是 p 点的有向距离
glm::vec2 ap = p - a;
float frac = glm::dot(ap, dir);
frac = glm::clamp(frac, 0.f, abLength);
glm::vec2 q = a + frac * dir;
glm::vec2 pq = q - p;

dist = glm::min(dist, length(pq));
}

return dist;
}

// p is world position
// float getDistance(glm::vec2 p) {
// // world position to sdf index
// int idx_x, idx_y;
// idx_x = int(glm::floor(p.x / sdfCellSize));
// idx_y = int(glm::floor(p.y / sdfCellSize));
//
// if (idx_x < 0 || idx_x > sdfWidth - 1) {
// return 9999.f;
// } else if (idx_y < 0.f || idx_y > sdfHeight - 1) {
// return 9999.f;
// } else {
// return grid.sdf.at<float>(Point(idx_x, idx_y));
// }
// }

// p is world position

void computeSdf(int sdfWidth, int sdfHeight, float sdfCellSize,
std::vector<Polygon> &polygons, Solver &slv) {
// compute sdf for (sdfWidth * sdfHeight) world space points
// the interval between two adjacent points is sdfCellSize
for (int x = 0; x < sdfWidth; x++) {
for (int y = 0; y < sdfHeight; y++) {
// std::cout << x << ", " << y << '\n';

// world space point
glm::vec2 p = worldOrigin + glm::vec2(sdfCellSize * x, sdfCellSize * y);

float fDist = 9999.f;
float temp = 0.f;

for (int i = 0; i < polygons.size(); i++) {
// std::cout << i << '\n';
temp = (inside_polygon(p, polygons[i])) ? -1.f : 1.f;
temp *= nearest_distance(p, polygons[i]);
// std::cout << "here" << '\n';

// fDist = glm::min(temp, fDist);
if (temp < fDist) {
fDist = temp;

// change to Node
// the nearest polygon to this node
// grid.polyPtrs.set(y, x, polygons[i]);
}
}

// save sdf distance
int idx = x + y * (sdfWidth - 1); // # of nodes in a row is (sdfWidth - 1)
slv.nodes[idx].sdfDist = fDist;
// std::cout << "(" << x << ", " << y << ") distance = " << fDist << '\n';
}
}
}
6 changes: 0 additions & 6 deletions src/sdf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,6 @@
#include <glm/gtx/compatibility.hpp>
#include <glm/gtx/string_cast.hpp>

extern glm::vec2 worldOrigin;

class Polygon {
public:
std::vector<glm::vec2> vertices;
Expand Down Expand Up @@ -51,7 +49,3 @@ class Polygon {
return polys;
}
}; // end class Polygon

bool intersect(glm::vec2, glm::vec2, glm::vec2, glm::vec2);
bool inside_polygon(glm::vec2, Polygon &);
float nearest_distance(glm::vec2, Polygon &);
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