From efb37b16186adafb38b4792c7360c38932d9355d Mon Sep 17 00:00:00 2001
From: austin <austin@austinhoover.net>
Date: Wed, 18 Dec 2024 17:43:32 -0500
Subject: [PATCH] fix gravity test

---
 src/main/c/includes/fluid/sim/pressurecell/solver_consts.h | 5 +++++
 src/main/c/src/fluid/sim/pressurecell/density.c            | 3 +++
 src/test/c/fluid/sim/pressurecell/add_gravity_tests.c      | 4 ++--
 src/test/c/fluid/sim/pressurecell/sim_e2e_tests.c          | 6 +++---
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/main/c/includes/fluid/sim/pressurecell/solver_consts.h b/src/main/c/includes/fluid/sim/pressurecell/solver_consts.h
index 8d8d0462..fa6dff4d 100644
--- a/src/main/c/includes/fluid/sim/pressurecell/solver_consts.h
+++ b/src/main/c/includes/fluid/sim/pressurecell/solver_consts.h
@@ -47,6 +47,11 @@
  */
 #define FLUID_PRESSURECELL_DIV_PRESSURE_CONST 5.0f
 
+/**
+ * Cutoff after which density is clamped to zero while diffusing
+ */
+#define FLUID_PRESSURECELL_MIN_DENSITY_CLAMP_CUTOFF 0.0001f
+
 /**
  * The number of times to relax most solvers
  */
diff --git a/src/main/c/src/fluid/sim/pressurecell/density.c b/src/main/c/src/fluid/sim/pressurecell/density.c
index 6d5778d5..81f5b96b 100644
--- a/src/main/c/src/fluid/sim/pressurecell/density.c
+++ b/src/main/c/src/fluid/sim/pressurecell/density.c
@@ -130,6 +130,9 @@ LIBRARY_API void pressurecell_diffuse_density(Environment * environment, Chunk *
                     )
                 ) * a
                 ;
+                if(densityTemp[IX(x,y,z)] < FLUID_PRESSURECELL_MIN_DENSITY_CLAMP_CUTOFF){
+                    densityTemp[IX(x,y,z)] = 0;
+                }
             }
         }
     }
diff --git a/src/test/c/fluid/sim/pressurecell/add_gravity_tests.c b/src/test/c/fluid/sim/pressurecell/add_gravity_tests.c
index 6de0b4d6..079d0e94 100644
--- a/src/test/c/fluid/sim/pressurecell/add_gravity_tests.c
+++ b/src/test/c/fluid/sim/pressurecell/add_gravity_tests.c
@@ -65,10 +65,10 @@ int fluid_sim_pressurecell_add_gravity_test1(){
     //
     expected = 0;
     actual = currentChunk->v[CENTER_LOC][IX(1,1,DIM-2)];
-    if(fabs(expected - actual) < 0.1f){
+    if(fabs(expected - actual) < FLUID_PRESSURE_CELL_ERROR_MARGIN){
         rVal++;
         printf("Gravity not applied!\n");
-        printf("%f \n", currentChunk->v[CENTER_LOC][IX(1,1,DIM-2)]);
+        printf("grav(1,1,DIM-2): %f \n", currentChunk->v[CENTER_LOC][IX(1,1,DIM-2)]);
     }
 
     return rVal;
diff --git a/src/test/c/fluid/sim/pressurecell/sim_e2e_tests.c b/src/test/c/fluid/sim/pressurecell/sim_e2e_tests.c
index 47cd5a2a..9b6d1391 100644
--- a/src/test/c/fluid/sim/pressurecell/sim_e2e_tests.c
+++ b/src/test/c/fluid/sim/pressurecell/sim_e2e_tests.c
@@ -95,10 +95,10 @@ int fluid_sim_pressurecell_sim_e2e_test2(){
     // cell that originall had values
     //
     expected = 0;
-    actual = currentChunk->d[CENTER_LOC][IX(1,2,DIM-2)];
+    actual = currentChunk->d[CENTER_LOC][IX(1,4,DIM-2)];
     if(fabs(expected - actual) > FLUID_PRESSURE_CELL_ERROR_MARGIN){
-        rVal += assertEqualsFloat(expected,actual,"Failed to recapture density into (1,2,DIM-2)!  expected: %f    actual: %f  \n");
-        printf("%f \n", currentChunk->v[CENTER_LOC][IX(1,2,DIM-2)]);
+        rVal += assertEqualsFloat(expected,actual,"Failed to recapture density into (1,4,DIM-2)!  expected: %f    actual: %f  \n");
+        printf("%f \n", currentChunk->v[CENTER_LOC][IX(1,4,DIM-2)]);
     }
 
     expected = MAX_FLUID_VALUE;