From b6c9873289968bf51989f3fefb86e5ceef8b6aaa Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Sun, 10 Apr 2016 15:27:21 -0600
Subject: [PATCH] light: return hit normal for DirtTrace

---
 include/light/light.h |  3 ++-
 light/ltface.c        | 17 ++++++++++++-----
 light/trace.c         |  2 +-
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/include/light/light.h b/include/light/light.h
index 1960d530..d2afb429 100644
--- a/include/light/light.h
+++ b/include/light/light.h
@@ -45,6 +45,7 @@ extern "C" {
 typedef struct traceinfo_s {
     vec3_t			point;
     const bsp2_dface_t          *face;
+    vec3_t  hitnormal;
     /* returns true if sky was hit. */
     bool hitsky;
     bool hitback;
@@ -99,7 +100,7 @@ int TraceLine(const dmodel_t *model, const int traceflags,
  */
 qboolean TestSky(const vec3_t start, const vec3_t dirn, const dmodel_t *self);
 qboolean TestLight(const vec3_t start, const vec3_t stop, const dmodel_t *self);
-qboolean DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out);
+qboolean DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out, vec3_t hitnormal_out);
 
 typedef struct {
     vec_t light;
diff --git a/light/ltface.c b/light/ltface.c
index 5a246b7e..d2cac3f6 100644
--- a/light/ltface.c
+++ b/light/ltface.c
@@ -594,7 +594,8 @@ CheckObstructed(const lightsurf_t *surf, const vec3_t offset, const vec_t us, co
             VectorAdd(testpoint, offset, testpoint);
             
             vec3_t hitpoint = {0};
-            if (DirtTrace(surf->midpoint, testpoint, surf->modelinfo->model, hitpoint)) {
+            vec3_t hitnormal = {0};
+            if (DirtTrace(surf->midpoint, testpoint, surf->modelinfo->model, hitpoint, hitnormal)) {
                 // make a corrected point
                 
                 vec3_t tracedir;
@@ -1440,7 +1441,7 @@ void SetupDirt( void ) {
  * ============
  */
 qboolean
-DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out)
+DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out, vec3_t hitnormal_out)
 {
     const modelinfo_t *const *model;
     traceinfo_t ti = {0};
@@ -1451,6 +1452,9 @@ DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hi
     if (self) {
         if (TraceFaces (&ti, self->headnode[0], start, stop)) {
             VectorCopy(ti.point, hitpoint_out);
+            if (hitnormal_out) {
+                VectorCopy(ti.hitnormal, hitnormal_out);
+            }
             return !ti.hitsky;
         }
     }
@@ -1461,6 +1465,9 @@ DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hi
             continue;
         if (TraceFaces (&ti, (*model)->model->headnode[0], start, stop)) {
             VectorCopy(ti.point, hitpoint_out);
+            if (hitnormal_out) {
+                VectorCopy(ti.hitnormal, hitnormal_out);
+            }
             return !ti.hitsky;
         }
     }
@@ -1526,7 +1533,7 @@ DirtForSample(const dmodel_t *model, const vec3_t origin, const vec3_t normal){
             VectorMA( origin, dirtDepth, direction, traceEnd );
 
             /* trace */
-            if (DirtTrace(origin, traceEnd, model, traceHitpoint)) {
+            if (DirtTrace(origin, traceEnd, model, traceHitpoint, NULL)) {
                 VectorSubtract( traceHitpoint, origin, displacement );
                 gatherDirt += 1.0f - ooDepth * VectorLength( displacement );
             }
@@ -1543,7 +1550,7 @@ DirtForSample(const dmodel_t *model, const vec3_t origin, const vec3_t normal){
             VectorMA( origin, dirtDepth, direction, traceEnd );
             
             /* trace */
-            if (DirtTrace(origin, traceEnd, model, traceHitpoint)) {
+            if (DirtTrace(origin, traceEnd, model, traceHitpoint, NULL)) {
                 VectorSubtract( traceHitpoint, origin, displacement );
                 gatherDirt += 1.0f - ooDepth * VectorLength( displacement );
             }
@@ -1554,7 +1561,7 @@ DirtForSample(const dmodel_t *model, const vec3_t origin, const vec3_t normal){
     VectorMA( origin, dirtDepth, normal, traceEnd );
     
     /* trace */
-    if (DirtTrace(origin, traceEnd, model, traceHitpoint)) {
+    if (DirtTrace(origin, traceEnd, model, traceHitpoint, NULL)) {
         VectorSubtract( traceHitpoint, origin, displacement );
         gatherDirt += 1.0f - ooDepth * VectorLength( displacement );
     }
diff --git a/light/trace.c b/light/trace.c
index 42227bb6..2eec8362 100644
--- a/light/trace.c
+++ b/light/trace.c
@@ -612,7 +612,7 @@ bool TraceFaces (traceinfo_t *ti, int node, const vec3_t start, const vec3_t end
             if (fi->content == CONTENTS_SOLID || fi->content == CONTENTS_SKY) {
                 ti->face = face;
                 ti->hitsky = (fi->content == CONTENTS_SKY);
-                
+                VectorCopy(fi->plane.normal, ti->hitnormal);
                 // check if we hit the back side
                 ti->hitback = (DotProduct(ti->dir, fi->plane.normal) >= 0);