zed-industries/zed · error

DirectX instance range exceeds the {} buffer

Error message

DirectX instance range exceeds the {} buffer

What it means

Guard in `draw_range`: `first_instance + instance_count` would run past the end of the allocated D3D11 instance buffer, so DrawInstanced would read out of bounds; the draw is rejected. Indicates an internal batching/offset bookkeeping bug rather than bad user input.

Source

Thrown at crates/gpui_windows/src/directx_renderer.rs:1119

        );
        unsafe {
            device_context.PSSetSamplers(0, Some(sampler));
            device_context.VSSetShaderResources(0, Some(texture));
            device_context.PSSetShaderResources(0, Some(texture));

            device_context.DrawInstanced(4, instance_count, 0, 0);
        }
        Ok(())
    }

    fn draw_range(
        &self,
        device_context: &ID3D11DeviceContext,
        batch_params_buffer: &ID3D11Buffer,
        first_instance: u32,
        instance_count: u32,
    ) -> Result<()> {
        anyhow::ensure!(
            first_instance as usize + instance_count as usize <= self.buffer_size,
            "DirectX instance range exceeds the {} buffer",
            self.label
        );
        update_batch_start(device_context, batch_params_buffer, first_instance)?;
        set_pipeline_state(
            device_context,
            slice::from_ref(&self.view),
            D3D_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP,
            &self.vertex,
            &self.fragment,
            &self.blend_state,
        );
        unsafe {
            device_context.DrawInstanced(4, instance_count, 0, 0);
        }
        Ok(())
    }

View on GitHub (pinned to f4178619ac)

Solutions

1. Fix upstream batch computation so ranges always fit the uploaded buffer.
2. Add assertions where instance ranges are computed to catch misbookkeeping early.
3. Re-upload the buffer if the previous frame's data was smaller than the requested range.
4. Log the buffer size vs requested range to locate the off-by-N bug.

When it happens

Trigger: Thrown at crates/gpui_windows/src/directx_renderer.rs:1119 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/0b41c12350e811d3. Report an issue: GitHub.