From 7272b080db41ef9033b83a991ee44e7a24176b62 Mon Sep 17 00:00:00 2001
From: epoch <epoch@hacking.allowed.org>
Date: Mon, 24 Feb 2020 00:49:21 -0600
Subject: made the camera control with the secondary mouse button work in a way
 that is easier to use

---
 src/graphics_c3.h | 2 ++
 src/mouse_x11.c   | 6 ++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/graphics_c3.h b/src/graphics_c3.h
index 691b650..b609721 100644
--- a/src/graphics_c3.h
+++ b/src/graphics_c3.h
@@ -23,6 +23,8 @@ struct gra_global {
   int mapxoff;
   int mapyoff;
   int mousemap[10];//you're only going to have 10 buttons on your mouse... right?
+  c2_t dragstart[10];//mouse coordinates where a drag was started
+  c3_rot_t oldcamera;
   int maxshapes;
 };
 
diff --git a/src/mouse_x11.c b/src/mouse_x11.c
index 23ec5ab..16c577c 100644
--- a/src/mouse_x11.c
+++ b/src/mouse_x11.c
@@ -38,12 +38,14 @@ int mouse_event_handler() {//this returns HVM_ key + for buttondown and - for bu
           printf("# gra_global.input_mode == %d\n",gra_global.input_mode);
         }
         printf("# button press %d\n",butt);
+        gra_global.dragstart[butt]=gra_global.mouse;
         gra_global.mousemap[butt]=1;
         redrawplzkthx=1;
         break;
       case ButtonRelease:
         printf("# button release %d\n",e.xbutton.button-1);
         gra_global.mousemap[e.xbutton.button-1]=-1;//we can trigger on -1 or on 1 then set back to 0 to prevent double-trigger
+        gra_global.oldcamera=global.camera.r;
         redrawplzkthx=1;
         break;
       case MotionNotify:
@@ -68,8 +70,8 @@ int mouse_event_handler() {//this returns HVM_ key + for buttondown and - for bu
     //global.camera.r.x.d=(gra_global.height - gra_global.mouse.y);//up and down camera controls backwards
     //fprintf(stderr,"# mouse.x: %f mouse.y: %f\n# width: %u height: %u\n",gra_global.mouse.x,gra_global.mouse.y,gra_global.width,gra_global.height);
     if(gra_global.mousemap[2] == 1) {//if "right" click is held down
-      global.camera.r.x.d=(gra_global.mouse.y);
-      global.camera.r.y.d=(gra_global.mouse.x);
+      global.camera.r.x.d=gra_global.oldcamera.x.d + (gra_global.mouse.y - gra_global.dragstart[2].y);
+      global.camera.r.y.d=gra_global.oldcamera.y.d + (gra_global.mouse.x - gra_global.dragstart[2].x);
     }
   }
   if(redrawplzkthx) {
-- 
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