From cf8e3fc935cc9187137dfc04ec4cfe7dddad2d3d Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Sun, 10 Apr 2016 22:29:59 -0600
Subject: [PATCH] light: augment DirtTrace with the hit plane

---
 include/light/light.h | 13 ++++++-------
 light/ltface.c        | 14 +++++++-------
 light/trace.c         |  4 +++-
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/include/light/light.h b/include/light/light.h
index 7221d3c2..7b3bf262 100644
--- a/include/light/light.h
+++ b/include/light/light.h
@@ -41,11 +41,15 @@ extern "C" {
 #define TRACE_HIT_LAVA  (1 << 3)
 #define TRACE_HIT_SKY   (1 << 4)
 
+typedef struct {
+    vec3_t normal;
+    vec_t dist;
+} plane_t;
 
 typedef struct traceinfo_s {
     vec3_t			point;
     const bsp2_dface_t          *face;
-    vec3_t  hitnormal;
+    plane_t  hitplane;
     /* returns true if sky was hit. */
     bool hitsky;
     bool hitback;
@@ -100,7 +104,7 @@ 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, vec3_t hitnormal_out);
+qboolean DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out, plane_t *hitplane_out);
 
 typedef struct {
     vec_t light;
@@ -126,11 +130,6 @@ typedef struct sun_s {
     float anglescale;
 } sun_t;
 
-typedef struct {
-    vec3_t normal;
-    vec_t dist;
-} plane_t;
-
 /* for vanilla this would be 18. some engines allow higher limits though, which will be needed if we're scaling lightmap resolution. */
 /*with extra sampling, lit+lux etc, we need at least 46mb stack space per thread. yes, that's a lot. on the plus side, it doesn't affect bsp complexity (actually, can simplify it a little)*/
 #define MAXDIMENSION (255+1)
diff --git a/light/ltface.c b/light/ltface.c
index 15ded1d9..c0333dfd 100644
--- a/light/ltface.c
+++ b/light/ltface.c
@@ -594,8 +594,8 @@ CheckObstructed(const lightsurf_t *surf, const vec3_t offset, const vec_t us, co
             VectorAdd(testpoint, offset, testpoint);
             
             vec3_t hitpoint = {0};
-            vec3_t hitnormal = {0};
-            if (DirtTrace(surf->midpoint, testpoint, surf->modelinfo->model, hitpoint, hitnormal)) {
+            plane_t hitplane = {0};
+            if (DirtTrace(surf->midpoint, testpoint, surf->modelinfo->model, hitpoint, &hitplane)) {
                 // make a corrected point
                 
                 vec3_t tracedir;
@@ -1442,7 +1442,7 @@ void SetupDirt( void ) {
  * ============
  */
 qboolean
-DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out, vec3_t hitnormal_out)
+DirtTrace(const vec3_t start, const vec3_t stop, const dmodel_t *self, vec3_t hitpoint_out, plane_t *hitplane_out)
 {
     const modelinfo_t *const *model;
     traceinfo_t ti = {0};
@@ -1453,8 +1453,8 @@ 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);
+            if (hitplane_out) {
+                *hitplane_out = ti.hitplane;
             }
             return !ti.hitsky;
         }
@@ -1466,8 +1466,8 @@ 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);
+            if (hitplane_out) {
+                *hitplane_out = ti.hitplane;
             }
             return !ti.hitsky;
         }
diff --git a/light/trace.c b/light/trace.c
index 439d832d..a4d8fb48 100644
--- a/light/trace.c
+++ b/light/trace.c
@@ -615,7 +615,9 @@ 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);
+                VectorCopy(fi->plane.normal, ti->hitplane.normal);
+                ti->hitplane.dist = fi->plane.dist;
+                
                 // check if we hit the back side
                 ti->hitback = (DotProduct(ti->dir, fi->plane.normal) >= 0);