move example to samples/systems

develop/samples/relations.lua

@@ -5,17 +5,32 @@ local evo = require 'evolved'
 evo.debug_mode(true)
 
 local fragments = {
-    planet = evo.builder():name('planet'):tag():spawn(),
-    spaceship = evo.builder():name('spaceship'):tag():spawn(),
+    planet = evo.builder()
+        :name('planet')
+        :tag()
+        :spawn(),
+    spaceship = evo.builder()
+        :name('spaceship')
+        :tag()
+        :spawn(),
 }
 
 local relations = {
-    docked_to = evo.builder():name('docked_to'):tag():explicit():spawn(),
+    docked_to = evo.builder()
+        :name('docked_to')
+        :tag()
+        :spawn(),
 }
 
 local planets = {
-    mars = evo.builder():name('Mars'):set(fragments.planet):spawn(),
-    venus = evo.builder():name('Venus'):set(fragments.planet):spawn(),
+    mars = evo.builder()
+        :name('Mars')
+        :set(fragments.planet)
+        :spawn(),
+    venus = evo.builder()
+        :name('Venus')
+        :set(fragments.planet)
+        :spawn(),
 }
 
 local spaceships = {

develop/samples/systems.lua

@@ -0,0 +1,129 @@
+---@diagnostic disable: unused-local
+
+local evo = require 'evolved'
+
+evo.debug_mode(true)
+
+---@class evolved.vector2
+---@field x number
+---@field y number
+
+---@param x number
+---@param y number
+---@return evolved.vector2
+---@nodiscard
+local function vector2(x, y)
+    ---@type evolved.vector2
+    return { x = x, y = y }
+end
+
+local consts = {
+    delta_time = 0.016,
+    physics_gravity = vector2(0, 9.81),
+}
+
+local groups = {
+    awake = evo.spawn(),
+    physics = evo.spawn(),
+    graphics = evo.spawn(),
+    shutdown = evo.spawn(),
+}
+
+local fragments = {
+    force = evo.spawn(),
+    position = evo.spawn(),
+    velocity = evo.spawn(),
+}
+
+local queries = {
+    physics_bodies = evo.builder()
+        :include(fragments.force, fragments.position, fragments.velocity)
+        :spawn(),
+}
+
+local awake_system = evo.builder()
+    :group(groups.awake)
+    :prologue(function()
+        print '-= | Awake | =-'
+        evo.builder()
+            :set(fragments.force, vector2(0, 0))
+            :set(fragments.position, vector2(0, 0))
+            :set(fragments.velocity, vector2(0, 0))
+            :spawn()
+    end):spawn()
+
+local integrate_forces_system = evo.builder()
+    :group(groups.physics)
+    :query(queries.physics_bodies)
+    :execute(function(chunk, entities, entity_count)
+        local delta_time, physics_gravity =
+            consts.delta_time, consts.physics_gravity
+
+        ---@type evolved.vector2[], evolved.vector2[]
+        local forces, velocities = chunk:components(
+            fragments.force, fragments.velocity)
+
+        for i = 1, entity_count do
+            local force, velocity = forces[i], velocities[i]
+
+            velocity.x = velocity.x + (physics_gravity.x + force.x) * delta_time
+            velocity.y = velocity.y + (physics_gravity.y + force.y) * delta_time
+        end
+    end):spawn()
+
+local integrate_velocities_system = evo.builder()
+    :group(groups.physics)
+    :query(queries.physics_bodies)
+    :execute(function(chunk, entities, entity_count)
+        local delta_time =
+            consts.delta_time
+
+        ---@type evolved.vector2[], evolved.vector2[], evolved.vector2[]
+        local forces, positions, velocities = chunk:components(
+            fragments.force, fragments.position, fragments.velocity)
+
+        for i = 1, entity_count do
+            local force, position, velocity = forces[i], positions[i], velocities[i]
+
+            position.x = position.x + velocity.x * delta_time
+            position.y = position.y + velocity.y * delta_time
+
+            force.x = 0
+            force.y = 0
+        end
+    end):spawn()
+
+local graphics_system = evo.builder()
+    :group(groups.graphics)
+    :query(queries.physics_bodies)
+    :execute(function(chunk, entities, entity_count)
+        ---@type evolved.vector2[]
+        local positions = chunk:components(
+            fragments.position)
+
+        for i = 1, entity_count do
+            local entity, position = entities[i], positions[i]
+
+            print(string.format(
+                '|-> {entity %d} at {%.4f, %.4f}',
+                entity, position.x, position.y))
+        end
+    end):spawn()
+
+local shutdown_system = evo.builder()
+    :group(groups.shutdown)
+    :epilogue(function()
+        print '-= | Shutdown | =-'
+        evo.batch_destroy(queries.physics_bodies)
+    end):spawn()
+
+do
+    evo.process(groups.awake)
+
+    for _ = 1, 10 do
+        evo.process(groups.physics)
+        evo.process(groups.graphics)
+    end
+
+    evo.process(groups.shutdown)
+end