EEVEE-Next: DoF: Avoid out of bound access in scatter vertex shader

As noted in the comment, it is very unlikely to happen.
But since we can run into undefined behavior if it does
better make the access safe.

source/blender/draw/engines/eevee_next/eevee_depth_of_field.cc

@@ -400,6 +400,7 @@ void DepthOfField::scatter_pass_sync()
     drw_pass.init();
     drw_pass.state_set(DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ADD_FULL);
     drw_pass.shader_set(inst_.shaders.static_shader_get(DOF_SCATTER));
+    drw_pass.bind_ubo("dof_buf", data_);
     drw_pass.push_constant("use_bokeh_lut", use_bokeh_lut_);
     drw_pass.bind_texture("bokeh_lut_tx", &bokeh_scatter_lut_tx_);
     drw_pass.bind_texture("occlusion_tx", &occlusion_tx_);

source/blender/draw/engines/eevee_next/shaders/eevee_depth_of_field_scatter_vert.glsl

@@ -14,6 +14,12 @@
 
 void main()
 {
+  if (gl_InstanceID >= dof_buf.scatter_max_rect) {
+    /* Very unlikely to happen but better avoid out of bound access. */
+    gl_Position = vec4(0.0);
+    return;
+  }
+
   ScatterRect rect = scatter_list_buf[gl_InstanceID];
 
   interp_flat.color_and_coc1 = rect.color_and_coc[0];

source/blender/draw/engines/eevee_next/shaders/infos/eevee_depth_of_field_info.hh

@@ -212,6 +212,7 @@ GPU_SHADER_CREATE_INFO(eevee_depth_of_field_scatter)
     .additional_info("eevee_shared", "draw_view")
     .sampler(0, ImageType::FLOAT_2D, "occlusion_tx")
     .sampler(1, ImageType::FLOAT_2D, "bokeh_lut_tx")
+    .uniform_buf(6, "DepthOfFieldData", "dof_buf")
     .storage_buf(0, Qualifier::READ, "ScatterRect", "scatter_list_buf[]")
     .fragment_out(0, Type::VEC4, "out_color")
     .push_constant(Type::BOOL, "use_bokeh_lut")