Fix draw state to be spawned on window.

Author: tychedelia

crates/processing_render/src/graphics.rs

@@ -29,7 +29,7 @@ use crate::{
     Flush,
     error::{ProcessingError, Result},
     image::{Image, bytes_to_pixels, create_readback_buffer, pixel_size, pixels_to_bytes},
-    render::command::{CommandBuffer, DrawCommand},
+    render::{RenderState, command::{CommandBuffer, DrawCommand}},
     surface::Surface,
 };
 
@@ -246,6 +246,7 @@ pub fn create(
                 Transform::from_xyz(0.0, 0.0, 999.9),
                 render_layer,
                 CommandBuffer::new(),
+                RenderState::default(),
                 SurfaceSize(width, height),
                 Graphics {
                     readback_buffer,
@@ -307,9 +308,21 @@ pub fn destroy(world: &mut World, entity: Entity) -> Result<()> {
     world.run_system_cached_with(destroy_inner, entity).unwrap()
 }
 
-pub fn begin_draw(_app: &mut App, _entity: Entity) -> Result<()> {
-    // nothing to do here for now
-    Ok(())
+pub fn begin_draw(world: &mut World, entity: Entity) -> Result<()> {
+    fn begin_draw_inner(
+        In(entity): In<Entity>,
+        mut state_query: Query<&mut RenderState>,
+    ) -> Result<()> {
+        let mut state = state_query
+            .get_mut(entity)
+            .map_err(|_| ProcessingError::GraphicsNotFound)?;
+        state.reset();
+        Ok(())
+    }
+
+    world
+        .run_system_cached_with(begin_draw_inner, entity)
+        .unwrap()
 }
 
 pub fn flush(app: &mut App, entity: Entity) -> Result<()> {

crates/processing_render/src/lib.rs

@@ -228,8 +228,8 @@ pub fn graphics_create(surface_entity: Entity, width: u32, height: u32) -> error
 }
 
 /// Begin a new draw pass for the graphics surface.
-pub fn graphics_begin_draw(_graphics_entity: Entity) -> error::Result<()> {
-    app_mut(|app| graphics::begin_draw(app, _graphics_entity))
+pub fn graphics_begin_draw(graphics_entity: Entity) -> error::Result<()> {
+    app_mut(|app| graphics::begin_draw(app.world_mut(), graphics_entity))
 }
 
 /// Flush current pending draw commands to the graphics surface.