Do collision checks in steps of the body's size

1 files changed, 51 insertions, 39 deletions

diff --git a/src/phys/world.odin b/src/phys/world.odin
index 15e7826..6ab12d5 100644
--- a/src/phys/world.odin
+++ b/src/phys/world.odin
@@ -2,6 +2,7 @@ package phys
 
 import "core:log"
 import "core:math"
+import "core:math/linalg"
 
 import rl "vendor:raylib"
 
@@ -203,57 +204,68 @@ update_body :: proc(h: Body_Handle) {
   rect := b.rect
   rect.start += b.pos
 
-  res_rect := b.rect
-  res_rect.start += res_pos
-
-  bin_list := _get_surrounding_bins(res_rect.start)
+  small_side := min(rect.size.x, rect.size.y)
+  steps := i32(math.ceil(linalg.length(b.vel * dt) / small_side))
 
   b.collisions = {}
 
-  for bin in bin_list {
-    for c_h in bin {
-      if c_h == h {
-        continue
-      }
+  for i in 0..<steps {
+    p := f32(i + 1) / f32(steps)
 
-      c := _get_body(c_h)
+    res_rect := b.rect
+    res_rect.start += b.pos + b.vel * dt * p
 
-      if b.mask & c.layers == {} {
-        continue
-      }
+    bin_list := _get_surrounding_bins(res_rect.start)
 
-      c_rect := c.rect
-      c_rect.start += c.pos
+    for bin in bin_list {
+      for c_h in bin {
+        if c_h == h {
+          continue
+        }
 
-      if aabb(res_rect, c_rect) {
-        if aabb_hori(rect, c_rect) {
-          if b.vel.y > 0 {
-            res_pos.y = c_rect.start.y - b.rect.size.y - b.rect.start.y
-            b.collisions += {.DOWN}
-          } else {
-            res_pos.y = c_rect.start.y + c_rect.size.y - b.rect.start.y
-            b.collisions += {.UP}
-          }
-          b.collisions += {.VERTICAL}
-        } else if aabb_vert(rect, c.rect) {
-          if b.vel.x > 0 {
-            res_pos.x = c_rect.start.x - b.rect.size.x - b.rect.start.x
-            b.collisions += {.LEFT}
-          } else {
-            res_pos.x = c_rect.start.x + c_rect.size.x - b.rect.start.x
-            b.collisions += {.RIGHT}
+        c := _get_body(c_h)
+
+        if b.mask & c.layers == {} {
+          continue
+        }
+
+        c_rect := c.rect
+        c_rect.start += c.pos
+
+        if aabb(res_rect, c_rect) {
+          if aabb_hori(rect, c_rect) {
+            if b.vel.y > 0 {
+              res_pos.y = c_rect.start.y - b.rect.size.y - b.rect.start.y
+              b.collisions += {.DOWN}
+              } else {
+                res_pos.y = c_rect.start.y + c_rect.size.y - b.rect.start.y
+                b.collisions += {.UP}
+              }
+              b.collisions += {.VERTICAL}
+            } else if aabb_vert(rect, c.rect) {
+              if b.vel.x > 0 {
+                res_pos.x = c_rect.start.x - b.rect.size.x - b.rect.start.x
+                b.collisions += {.LEFT}
+              } else {
+                res_pos.x = c_rect.start.x + c_rect.size.x - b.rect.start.x
+                b.collisions += {.RIGHT}
+              }
+              b.collisions += {.HORIZONTAL}
           }
-          b.collisions += {.HORIZONTAL}
         }
       }
     }
-  }
 
-  if .HORIZONTAL in b.collisions {
-    b.vel.x = 0
-  }
-  if .VERTICAL in b.collisions {
-    b.vel.y = 0
+    if .HORIZONTAL in b.collisions {
+      b.vel.x = 0
+    }
+    if .VERTICAL in b.collisions {
+      b.vel.y = 0
+    }
+
+    if b.collisions != nil {
+      break
+    }
   }
 
   set_position(h, res_pos)