From 3a2bc7664336fc386cde95dbdd3ca782b89cf0ac Mon Sep 17 00:00:00 2001
From: Simon <simon@hardwired.org.uk>
Date: Tue, 4 Jan 2011 13:35:16 +0000
Subject: [PATCH] Gravity control by Moach

---
 includes/defines.h   |  3 +++
 includes/interface.h |  1 +
 includes/powder.h    |  2 ++
 src/main.c           | 26 ++++++++++++++++++++++++++
 src/powder.c         | 44 ++++++++++++++++++++++++++++++++++----------
 5 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/includes/defines.h b/includes/defines.h
index bf2e06234..b2bec4e5b 100644
--- a/includes/defines.h
+++ b/includes/defines.h
@@ -28,6 +28,9 @@
 #define YRES	384
 #define NPART XRES*YRES
 
+#define XCNTR   306
+#define YCNTR   192
+
 #define MAX_DISTANCE sqrt(pow(XRES, 2)+pow(YRES, 2))
 
 #define MAXSIGNS 16
diff --git a/includes/interface.h b/includes/interface.h
index dcbd99704..159e2472f 100644
--- a/includes/interface.h
+++ b/includes/interface.h
@@ -125,6 +125,7 @@ extern int svf_publish;
 extern char svf_id[16];
 extern char svf_name[64];
 extern char svf_tags[256];
+extern char svf_description[255];
 extern void *svf_last;
 extern int svf_lsize;
 
diff --git a/includes/powder.h b/includes/powder.h
index 944087e21..12baf8851 100644
--- a/includes/powder.h
+++ b/includes/powder.h
@@ -652,6 +652,8 @@ extern float player[27];
 
 extern float player2[27];
 
+extern int gravityMode;
+
 extern particle *parts;
 extern particle *cb_parts;
 
diff --git a/src/main.c b/src/main.c
index 7c24475e4..25a250351 100644
--- a/src/main.c
+++ b/src/main.c
@@ -477,6 +477,7 @@ int parse_save(void *save, int size, int replace, int x0, int y0)
 
     if(replace)
     {
+		gravityMode = 1;
         memset(bmap, 0, sizeof(bmap));
         memset(emap, 0, sizeof(emap));
         memset(signs, 0, sizeof(signs));
@@ -1515,6 +1516,29 @@ int main(int argc, char *argv[])
 	    else 
 		GRID_MODE = (GRID_MODE+1)%10;
 	}
+		
+		if(sdl_key=='w') //Gravity, by Moach
+		{
+			++gravityMode; // cycle gravity mode
+			itc = 51;
+			
+			switch (gravityMode)
+			{
+				default:
+					gravityMode = 0;
+				case 0:
+					strcpy(itc_msg, "Gravity: Off");
+					break;
+				case 1:
+					strcpy(itc_msg, "Gravity: Vertical");
+					break;
+				case 2:
+					strcpy(itc_msg, "Gravity: Radial");
+					break;
+					
+			}
+		}
+		
 	if(sdl_key=='t')
             VINE_MODE = !VINE_MODE;
         if(sdl_key==SDLK_SPACE)
@@ -2033,6 +2057,8 @@ int main(int argc, char *argv[])
                         svf_id[0] = 0;
                         svf_name[0] = 0;
                         svf_tags[0] = 0;
+						svf_description[0] = 0;
+						gravityMode = 1;
 
                         memset(fire_bg, 0, XRES*YRES*PIXELSIZE);
                         memset(fire_r, 0, sizeof(fire_r));
diff --git a/src/powder.c b/src/powder.c
index f61d6d594..a515177d5 100644
--- a/src/powder.c
+++ b/src/powder.c
@@ -12,6 +12,8 @@ float player2[27];
 particle *parts;
 particle *cb_parts;
 
+int gravityMode = 1; // starts enabled in "vertical" mode...
+
 unsigned char bmap[YRES/CELL][XRES/CELL];
 unsigned char emap[YRES/CELL][XRES/CELL];
 
@@ -1073,6 +1075,8 @@ void update_particles_i(pixel *vid, int start, int inc)
     float c_heat = 0.0f;
     int h_count = 0;
     int starti = (start*-1);
+	float pGravX, pGravY, pGravD;
+	
 	if(sys_pause&&!framerender)
                 return;
     if(ISGRAV==1)
@@ -1500,16 +1504,36 @@ void update_particles_i(pixel *vid, int start, int inc)
             }
             else
             {
-		if(t==PT_ANAR)
-		{
-			parts[i].vx -= ptypes[t].advection*vx[y/CELL][x/CELL];
-			parts[i].vy -= ptypes[t].advection*vy[y/CELL][x/CELL] + ptypes[t].gravity;
-		}
-		else{
-                parts[i].vx += ptypes[t].advection*vx[y/CELL][x/CELL];
-                parts[i].vy += ptypes[t].advection*vy[y/CELL][x/CELL] + ptypes[t].gravity;
-		
-		}
+				//Gravity mode by Moach
+				switch (gravityMode)
+				{
+					default:
+					case 0:
+						pGravX = pGravY = 0.0f;
+						break;
+					case 1:
+						pGravX = 0.0f;
+						pGravY = ptypes[t].gravity;
+						break;
+					case 2:
+						
+						pGravD = 0.01f - hypotf((x - XCNTR), (y - YCNTR)); 
+						
+						pGravX = ptypes[t].gravity * ((float)(x - XCNTR) / pGravD);
+						pGravY = ptypes[t].gravity * ((float)(y - YCNTR) / pGravD);
+						
+				}
+				
+				if(t==PT_ANAR)
+				{
+					parts[i].vx -= ptypes[t].advection*vx[y/CELL][x/CELL] + pGravX;
+					parts[i].vy -= ptypes[t].advection*vy[y/CELL][x/CELL] + pGravY;
+				}
+				else{
+					parts[i].vx += ptypes[t].advection*vx[y/CELL][x/CELL] + pGravX;
+					parts[i].vy += ptypes[t].advection*vy[y/CELL][x/CELL] + pGravY;
+					
+				}
             }
 
             if(ptypes[t].diffusion)