From 3f479e470f2650f73161f3988b23ba150783d161 Mon Sep 17 00:00:00 2001
From: Ketmar Dark <ketmar@ketmar.no-ip.org>
Date: Sun, 17 Apr 2016 15:15:58 +0300
Subject: [PATCH] new tracer

---
 data/shaders/srlight_trace.frag | 98 +++++++++++++++++++++++++----------------
 1 file changed, 60 insertions(+), 38 deletions(-)

diff --git a/data/shaders/srlight_trace.frag b/data/shaders/srlight_trace.frag
index cd4aab4..1a61dcf 100644
--- a/data/shaders/srlight_trace.frag
+++ b/data/shaders/srlight_trace.frag
@@ -19,7 +19,7 @@
 
 #define HUMANIOD_THETA
 
-#define INTO_DEPTH  (4.0)
+#define INTO_DEPTH  (6)
 
 #define PI  (3.14159265)
 
@@ -35,6 +35,31 @@ uniform vec2 mapPixSize; // size of occluders map
 #define THRESHOLD  (0.75)
 
 
+#define TRACE_STEP  do { \
+  vec2 nextTraceCell = vec2(0, 0); \
+  float t = 1e10; \
+  float tempT = 1e10; \
+  if (ab.x > 0.0 && testX) { \
+    tempT = -(-r0.x+(currentTraceCell.x+1.0))/(-ab.x); \
+    if (tempT >= 0.0) { t = tempT; nextTraceCell = vec2(1.0, 0.0); } \
+  } \
+  if (ab.y > 0.0 && testY) { \
+    tempT = -(-r0.y+(currentTraceCell.y+1.0))/(-ab.y); \
+    if (tempT < t && tempT >= 0.0) { t = tempT; nextTraceCell = vec2(0.0, 1.0); } \
+  } \
+  if (ab.x < 0.0 && testX) { \
+    tempT = -(r0.x-(currentTraceCell.x-1.0))/(ab.x); \
+    if (tempT < t && tempT >= 0.0) { t = tempT; nextTraceCell = vec2(-1.0, 0.0); } \
+  } \
+  if (ab.y < 0.0 && testY) { \
+    tempT = -(r0.y-(currentTraceCell.y-1.0))/(ab.y); \
+    if (tempT < t && tempT >= 0.0) { t = tempT; nextTraceCell = vec2(0.0, -1.0); } \
+  } \
+  r0 += ab*t; \
+  currentTraceCell += nextTraceCell; \
+} while (false)
+
+
 void main (void) {
   //float dmposx = gl_TexCoord[0].x;
   //vec2 ltPos = lightPos/mapPixSize;
@@ -55,46 +80,43 @@ void main (void) {
 #endif
     float nsint = -sin(theta);
     float ncost = cos(theta);
-    float dst = 0.0;
-    while (dst < lightTexSize.x/2.0) {
-      // sample the occlusion map
-      ltPos = lightPos+vec2(nsint*dst, ncost*dst);
-      vec2 ltsmPos = vec2(floor(ltPos.x/8), floor(ltPos.y/8));
-      ltsmPos = ltsmPos*8+0.5;
-      if (texture2D(texOccSmall, ltsmPos/mapPixSize).a <= THRESHOLD) {
-        //dst = min(dst+8.0, lightTexSize.x/2.0);
-        dst += 3.0;
-      } else {
-        ltPos /= mapPixSize;
-        float dataa = texture2D(texOccFull, ltPos).a;
-        // if we've hit an opaque fragment (occluder), then get new distance
-        // if the new distance is below the current, then we'll use that for our ray
-        if (dataa > THRESHOLD) {
-  #ifdef INTO_DEPTH
-          // if we hit occluders, trace through it for some more steps, so blur will look better on hitpoints
-          float orgDst = dst;
-          for (float count = 0.0; count <= INTO_DEPTH; count += 1.0) {
-            dst += 1.0;
-            ltPos = (lightPos+vec2(nsint*dst, ncost*dst))/mapPixSize;
-            dataa = texture2D(texOccFull, ltPos).a;
-            if (dataa <= THRESHOLD) {
-              dst -= 1.0;
-              break;
-            }
-          }
-  #else
-          //dst = max(0.0, dst-ltsyStep);
-          //dst = max(0.0, dst-1.0);
-  #endif
-          break; // the current distance is how far from the top we've come
+
+    vec2 a = lightPos;
+    vec2 b = a+normalize(vec2(nsint, ncost))*(lightTexSize.x/2);
+
+    vec2 ab = b-a;
+    float lengthAB = length(ab);
+    ab /= lengthAB;
+    vec2 r0 = a;
+    float lengthABSqr = lengthAB*lengthAB;
+    bool testX = abs(ab.x) > 1e-4;
+    bool testY = abs(ab.y) > 1e-4;
+    vec2 currentTraceCell = floor(lightPos);
+
+    float dst = 1.0;
+
+    while (dot(r0-a, r0-a) < lengthABSqr) {
+      float dataa = texture2D(texOccFull, currentTraceCell/mapPixSize).a;
+      if (dataa > THRESHOLD) {
+        vec2 lastHit = r0;
+#ifdef INTO_DEPTH
+        // do some steps
+        for (int stp = INTO_DEPTH; stp > 0; --stp) {
+          TRACE_STEP;
+          dataa = texture2D(texOccFull, currentTraceCell/mapPixSize).a;
+          if (dataa <= THRESHOLD) break;
+          lastHit = r0;
         }
-        dst += 1.0;
+#endif
+        dst = distance(lightPos, lastHit)/(lightTexSize.x/2.0);
+        break;
       }
+      TRACE_STEP;
     }
-    //dst = distance(lightPos, lightPos+vec2(nsint*dst, ncost*dst));
-    dst /= lightTexSize.x;
-    dst *= 2.0;
-    dst = min(dst, 1.0);
+
+    //dst /= lightTexSize.x;
+    //dst *= 2.0;
+    dst = max(min(dst, 1.0), 0.0);
     gl_FragColor = vec4(vec3(dst), 1.0);
   }
 }
-- 
2.11.4.GIT