From 7256502afa0babe60fcafbd2888cd3e33c3f9b6b Mon Sep 17 00:00:00 2001
From: xolatile
Date: Wed, 16 Jul 2025 23:07:43 +0200
Subject: Source code, broken...

---
 src/engine/lightning.h | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 src/engine/lightning.h

(limited to 'src/engine/lightning.h')

diff --git a/src/engine/lightning.h b/src/engine/lightning.h
new file mode 100644
index 0000000..bc6e21c
--- /dev/null
+++ b/src/engine/lightning.h
@@ -0,0 +1,123 @@
+#define MAXLIGHTNINGSTEPS 64
+#define LIGHTNINGSTEP 8
+int lnjitterx[2][MAXLIGHTNINGSTEPS], lnjittery[2][MAXLIGHTNINGSTEPS];
+int lnjitterframe = 0, lastlnjitter = 0;
+
+VAR(lnjittermillis, 0, 100, 1000);
+VAR(lnjitterradius, 0, 4, 100);
+FVAR(lnjitterscale, 0, 0.5f, 10);
+VAR(lnscrollmillis, 1, 300, 5000);
+FVAR(lnscrollscale, 0, 0.125f, 10);
+FVAR(lnblendpower, 0, 0.25f, 1000);
+
+static void calclightningjitter(int frame)
+{
+    loopi(MAXLIGHTNINGSTEPS)
+    {
+        lnjitterx[lnjitterframe][i] = -lnjitterradius + rnd(2*lnjitterradius + 1);
+        lnjittery[lnjitterframe][i] = -lnjitterradius + rnd(2*lnjitterradius + 1);
+    }
+}
+
+static void setuplightning()
+{
+    if(!lastlnjitter || lastmillis-lastlnjitter > lnjittermillis)
+    {
+        if(!lastlnjitter) calclightningjitter(lnjitterframe);
+        lastlnjitter = lastmillis - (lastmillis%lnjittermillis);
+        calclightningjitter(lnjitterframe ^= 1);
+    }
+}
+
+static void renderlightning(Texture *tex, const vec &o, const vec &d, float sz)
+{
+    vec step(d);
+    step.sub(o);
+    float len = step.magnitude();
+    int numsteps = clamp(int(ceil(len/LIGHTNINGSTEP)), 2, MAXLIGHTNINGSTEPS);
+    step.div(numsteps+1);
+    int jitteroffset = detrnd(int(d.x+d.y+d.z), MAXLIGHTNINGSTEPS);
+    vec cur(o), up, right;
+    up.orthogonal(step);
+    up.normalize();
+    right.cross(up, step);
+    right.normalize();
+    float scroll = -float(lastmillis%lnscrollmillis)/lnscrollmillis, 
+          scrollscale = lnscrollscale*(LIGHTNINGSTEP*tex->ys)/(sz*tex->xs),
+          blend = pow(clamp(float(lastmillis - lastlnjitter)/lnjittermillis, 0.0f, 1.0f), lnblendpower),
+          jitter0 = (1-blend)*lnjitterscale*sz/lnjitterradius, jitter1 = blend*lnjitterscale*sz/lnjitterradius; 
+    gle::begin(GL_TRIANGLE_STRIP);
+    loopj(numsteps)
+    {
+        vec next(cur);
+        next.add(step);
+        if(j+1==numsteps) next = d;
+        else
+        {
+            int lj = (j+jitteroffset)%MAXLIGHTNINGSTEPS;
+            next.add(vec(right).mul((jitter1*lnjitterx[lnjitterframe][lj] + jitter0*lnjitterx[lnjitterframe^1][lj])));
+            next.add(vec(up).mul((jitter1*lnjittery[lnjitterframe][lj] + jitter0*lnjittery[lnjitterframe^1][lj])));
+        }
+        vec dir1 = next, dir2 = next, across;
+        dir1.sub(cur);
+        dir2.sub(camera1->o);
+        across.cross(dir2, dir1).normalize().mul(sz);
+        gle::attribf(cur.x-across.x, cur.y-across.y, cur.z-across.z);
+            gle::attribf(scroll, 1);
+        gle::attribf(cur.x+across.x, cur.y+across.y, cur.z+across.z);
+            gle::attribf(scroll, 0);
+        scroll += scrollscale;
+        if(j+1==numsteps)
+        {
+            gle::attribf(next.x-across.x, next.y-across.y, next.z-across.z);
+                gle::attribf(scroll, 1);
+            gle::attribf(next.x+across.x, next.y+across.y, next.z+across.z);
+                gle::attribf(scroll, 0);
+        }
+        cur = next;
+    }
+    gle::end();
+}
+
+struct lightningrenderer : listrenderer
+{
+    lightningrenderer()
+        : listrenderer("packages/particles/lightning.jpg", 2, PT_LIGHTNING|PT_TRACK|PT_GLARE)
+    {}
+
+    void startrender()
+    {
+        glDisable(GL_CULL_FACE);
+        gle::defattrib(gle::ATTRIB_VERTEX, 3, GL_FLOAT);
+        gle::defattrib(gle::ATTRIB_TEXCOORD0, 2, GL_FLOAT);
+    }
+
+    void endrender()
+    {
+        glEnable(GL_CULL_FACE);
+    }
+
+    void update()
+    {
+        setuplightning();
+    }
+
+    void seedemitter(particleemitter &pe, const vec &o, const vec &d, int fade, float size, int gravity)
+    {
+        pe.maxfade = max(pe.maxfade, fade);
+        pe.extendbb(o, size);
+        pe.extendbb(d, size);
+    }
+
+    void renderpart(listparticle *p, const vec &o, const vec &d, int blend, int ts)
+    {
+        blend = min(blend<<2, 255);
+        if(type&PT_MOD) //multiply alpha into color
+            gle::colorub((p->color.r*blend)>>8, (p->color.g*blend)>>8, (p->color.b*blend)>>8);
+        else
+            gle::color(p->color, blend);
+        renderlightning(tex, o, d, p->size);
+    }
+};
+static lightningrenderer lightnings;
+
-- 
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