add Physics_Body and basic move_body

settings.cfg

@@ -1,4 +1,4 @@
-master_volume 0.15
+master_volume 0
 music_volume 1
 sfx_volume 1
 fullscreen 0

src/pseudophysics/core.jai

@@ -1,2 +1,86 @@
 #load "colliders.jai";
 #load "worldphysics.jai";
+
+Physics_Body :: struct {
+	half_extents : Vector3;
+	velocity     : Vector3;
+	position     : Vector3;
+
+	// Status, don't write to these outside of the engine physics code:
+	on_ground   : bool;
+	hit_x       : bool;
+	hit_y       : bool;
+	hit_z       : bool;
+
+	// Config:
+	prevent_falling     : bool = true;
+	max_step_height     : float = 0.0;
+	gravity             : float = 20;
+	downward_probe_dist : float = 0.01;
+}
+
+move_body :: (body : *Physics_Body, dt: float) {
+	// reset status
+	body.on_ground = false;
+	body.hit_x = false;
+	body.hit_y = false;
+	body.hit_z = false;
+
+
+	// apply velocity XZ
+	body.position.x += body.velocity.x * dt;
+	if body_overlaps_solid(body) {
+		body.hit_x = true;
+		if body.velocity.x < 0 {
+			hit_cell := floor(body.position.x - body.half_extents.x);
+			body.position.x = hit_cell + 1.0 + body.half_extents.x;
+		} else {
+			hit_cell := floor(body.position.x + body.half_extents.x);
+			body.position.x = hit_cell - body.half_extents.x;
+		}
+		body.velocity.x = 0;
+	}
+
+	body.position.z+= body.velocity.z * dt;
+	if body_overlaps_solid(body) {
+		body.hit_z = true;
+		if body.velocity.z < 0 {
+			hit_cell := floor(body.position.z - body.half_extents.z);
+			body.position.z = hit_cell + 1.0 + body.half_extents.z;
+		} else {
+			hit_cell := floor(body.position.z + body.half_extents.z);
+			body.position.z = hit_cell - body.half_extents.z;
+		}
+		body.velocity.z = 0;
+	}
+	
+	// gravity
+	probe_body := body.*;
+	probe_body.position.y -= body.downward_probe_dist;
+	if body.velocity.y <= 0 && body_overlaps_solid(*probe_body) {
+		// Do this so we don't stutter on the ground
+		body.hit_y = true;
+		body.on_ground = true;
+		body.velocity.y = 0;
+		hit_cell := floor(probe_body.position.y - body.half_extents.y);
+		body.position.y = hit_cell + 1.0 + body.half_extents.y;
+	} else {
+		body.velocity.y -= body.gravity * dt;
+	}
+
+	// apply velocity Y
+	body.position.y += body.velocity.y * dt;
+	if body_overlaps_solid(body) {
+		body.hit_y = true;
+		if body.velocity.y < 0 {
+			body.on_ground = true;
+			hit_cell := floor(body.position.y - body.half_extents.y);
+			body.position.y = hit_cell + 1.0 + body.half_extents.y;
+		} else {
+			hit_cell := floor(body.position.y + body.half_extents.y);
+			body.position.y = hit_cell - body.half_extents.y;
+		}
+		body.velocity.y = 0;
+	}
+
+}

src/pseudophysics/worldphysics.jai

@@ -1,7 +1,4 @@
-is_trile_collision :: (fx: float, fy: float, fz: float) -> bool {
-	x := cast(s32)floor(fx);
-	y := cast(s32)floor(fy);
-	z := cast(s32)floor(fz);
+is_cell_solid :: (x : s32, y : s32, z : s32) -> bool {
 	world := get_current_world();
 	if !world.valid then return false;
 	
@@ -12,3 +9,36 @@ is_trile_collision :: (fx: float, fy: float, fz: float) -> bool {
     lx, ly, lz := world_to_local(x, y, z);
 	return chunk_get_occupancy_mask_at(chunk, lx, ly, lz) != .FREE;
 }
+
+is_trile_collision :: (fx: float, fy: float, fz: float) -> bool {
+	x := cast(s32)floor(fx);
+	y := cast(s32)floor(fy);
+	z := cast(s32)floor(fz);
+	return is_cell_solid(x, y, z);
+}
+
+// A little bit of leeway into collisions so we aren't jittering
+SKIN :: 0.001;
+
+body_overlaps_solid :: (body : *Physics_Body) -> bool {
+	max := body.position + body.half_extents;
+	min := body.position - body.half_extents;
+
+	min_x := cast(s32)floor(min.x + SKIN);
+	min_y := cast(s32)floor(min.y + SKIN);
+	min_z := cast(s32)floor(min.z + SKIN);
+	max_x := cast(s32)floor(max.x - SKIN);
+	max_y := cast(s32)floor(max.y - SKIN);
+	max_z := cast(s32)floor(max.z - SKIN);
+
+	for x : min_x..max_x {
+		for y : min_y..max_y {
+			for z : min_z..max_z {
+				if is_cell_solid(x,y,z) {
+					return true;
+				}
+			}
+		}
+	}
+	return false;
+}