add beginGeometry

Author: Nitish-bot

crates/processing_pyo3/src/graphics.rs

@@ -308,6 +308,11 @@ impl Graphics {
         graphics_ortho(self.entity, left, right, bottom, top, near, far)
             .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
     }
+
+    pub fn begin_geometry(&self) -> PyResult<()> {
+        geometry_begin(self.entity)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
 }
 
 // TODO: a real color type. or color parser? idk. color is confusing. let's think

crates/processing_pyo3/src/lib.rs

@@ -40,7 +40,8 @@ fn processing(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(rect, m)?)?;
     m.add_function(wrap_pyfunction!(image, m)?)?;
     m.add_function(wrap_pyfunction!(draw_geometry, m)?)?;
-
+    m.add_function(wrap_pyfunction!(begin_geometry, m)?)?;
+    
     Ok(())
 }
 
@@ -223,3 +224,9 @@ fn rect(
 fn image(module: &Bound<'_, PyModule>, image_file: &str) -> PyResult<Image> {
     get_graphics(module)?.image(image_file)
 }
+
+#[pyfunction]
+#[pyo3(pass_module)]
+fn begin_geometry(module: &Bound<'_, PyModule>) -> PyResult<()> {
+    get_graphics(module)?.begin_geometry()
+}

crates/processing_render/src/geometry/mod.rs

@@ -16,7 +16,7 @@ use bevy::{
     render::render_resource::PrimitiveTopology,
 };
 
-use crate::error::{ProcessingError, Result};
+use crate::{error::{ProcessingError, Result}, render::RenderState};
 
 pub struct GeometryPlugin;
 
@@ -365,3 +365,33 @@ pub fn destroy(
     commands.entity(entity).despawn();
     Ok(())
 }
+
+pub fn begin(
+    In(graphics_entity): In<Entity>,
+    mut commands: Commands,
+    mut state_query: Query<&mut RenderState>,
+    mut meshes: ResMut<Assets<Mesh>>,
+    builtins: Res<BuiltinAttributes>,
+) -> Result<()> {    
+    let layout_entity = commands
+        .spawn(VertexLayout::with_attributes(vec![
+            builtins.position,
+            builtins.normal,
+            builtins.color,
+            builtins.uv,
+        ]))
+        .id();
+
+    let mesh = Mesh::new(
+        Topology::TriangleList.to_primitive_topology(),
+        RenderAssetUsages::default(),
+    );
+    let handle = meshes.add(mesh);
+    
+    let mut state = state_query
+        .get_mut(graphics_entity)
+        .map_err(|_| ProcessingError::GraphicsNotFound)?;
+
+    state.running_geometry = Some(Geometry::new(handle, layout_entity));
+    Ok(())
+}

crates/processing_render/src/lib.rs

@@ -1071,3 +1071,12 @@ pub fn geometry_box(width: f32, height: f32, depth: f32) -> error::Result<Entity
             .unwrap())
     })
 }
+
+pub fn geometry_begin(graphics_entity: Entity) -> error::Result<()> {
+    app_mut(|app| {
+        app
+            .world_mut()
+            .run_system_cached_with(geometry::begin, graphics_entity)
+            .unwrap()
+    })
+}