From 73197756c81279e8a0e8533b783764e2fe60de19 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Mon, 4 Feb 2019 16:18:53 -0800
Subject: [PATCH] Added file

---
 explosion.h | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 explosion.h

diff --git a/explosion.h b/explosion.h
new file mode 100644
index 0000000..f52d8c0
--- /dev/null
+++ b/explosion.h
@@ -0,0 +1,105 @@
+/**
+  * ASCII explosion from squeamish ossifrage at:
+  * https://codegolf.stackexchange.com/questions/24462/display-the-explosion-of-a-star-in-ascii-art/24554#24554
+  */
+#include "colors.h"
+#include <curses.h>
+#include <math.h>
+#include <stdlib.h>
+
+#define NUM_BLOBS 800
+#define PERSPECTIVE 50.0
+
+typedef struct {
+    double x,y,z;
+} spaceblob_t;
+
+static double prng() {
+    static long long s=1;
+    s = s * 1488248101 + 981577151;
+    return ((s % 65536) - 32768) / 32768.0;
+}
+
+void draw_explosion(int i, int midx, int midy) {
+    static spaceblob_t blobs[NUM_BLOBS];
+    int rows,cols;
+    getmaxyx(stdscr,rows,cols);
+    int maxx,minx,maxy,miny;
+    minx = -midx;
+    maxx = cols+minx-1;
+    miny = -midy;
+    maxy = rows+miny-1;
+
+    if (i == 0) {
+        /* Generate random blob coordinates */
+        for (int i=0; i<NUM_BLOBS; i++) {
+            double bx,by,bz,br;
+            bx = prng();
+            by = prng();
+            bz = prng();
+            br = sqrt(bx*bx + by*by + bz*bz);
+            blobs[i].x = (bx / br) * (1.3 + 0.2 * prng());
+            blobs[i].y = (0.5 * by / br) * (1.3 + 0.2 * prng());;
+            blobs[i].z = (bz / br) * (1.3 + 0.2 * prng());;
+        }
+        /* Flash on the first frame */
+        bkgd(COLOR_PAIR(WHITE_BG));
+        erase();
+        return;
+    }
+
+    bkgd(0);
+    chtype line[cols+1];
+    for (int y=miny; y<=maxy; y++) {
+        int row = y+midy;
+        for (int x=minx; x<=maxx; x++) {
+            int col = x+midx;
+            /* Show expanding star in next 7 frames */
+            if (i<8) {
+                double r = sqrt(x*x + 4*y*y);
+                if (r < i*2)
+                    mvaddch(row,col,'@');
+                continue;
+            }
+
+            /* Otherwise show blast wave */
+            double r = sqrt(x*x + 4*y*y) * (0.5 + (prng()/3.0)*cos(16.*atan2(y*2.+0.01,x+0.01))*.3);
+            int v = i - r - 7;
+            if (v<0) {
+                if (i<19) {
+                    int attr = 0;//color_ramp1[i-8];
+                    line[col] = "%@W#H=+~-:."[i-8] | attr;
+                } else {
+                    line[col] = ' ';
+                }
+            } else if (v<20) {
+                int attr = 0;//color_ramp2[v];
+                line[col] = " .:!HIOMW#%$&@08O=+-"[v] | attr;
+            } else {
+                line[col] = ' ';
+            }
+        }
+        if (i >= 8) {
+            line[cols+1] = '\0';
+            mvaddchstr(row,0,line);
+        }
+    }
+
+    /* Add blobs with perspective effect */
+    if (i>6) {
+        int i0 = i-6;
+        for (int j=0; j<NUM_BLOBS; j++) {
+            double bx = blobs[j].x * i0;
+            double by = blobs[j].y * i0;
+            double bz = blobs[j].z * i0;
+            if (bz<5-PERSPECTIVE || bz>PERSPECTIVE) continue;
+            int x = midx + bx * PERSPECTIVE / (bz+PERSPECTIVE);
+            int y = midy + by * PERSPECTIVE / (bz+PERSPECTIVE);
+            if (x>=0 && x<cols && y>=0 && y<rows) {
+                int row = y, col = x;
+                mvaddch(row,col,(bz>40) ? '.' : (bz>-20) ? 'o' : '@');
+            }
+        }
+    }
+}
+