#version 450

// iter13 XFB probe vertex shader.
// Writes a known pattern per vertex into transform feedback buffer 0.
// Each vertex emits one vec4: (vertex_id, instance_id, 0x1234, 0xcafe).
// With a 3-vertex single-instance draw + buffer offset 0,
// expected capture (LE float32 array of vec4s):
//   vertex 0: 0.0, 0.0, 4660.0, 51966.0
//   vertex 1: 1.0, 0.0, 4660.0, 51966.0
//   vertex 2: 2.0, 0.0, 4660.0, 51966.0

layout(xfb_buffer = 0, xfb_offset = 0, xfb_stride = 16, location = 0) out vec4 captured;

void main() {
    // Position is unused (rasterizerDiscardEnable=VK_TRUE) but needed for valid pipeline.
    gl_Position = vec4(0, 0, 0, 1);

    captured = vec4(
        float(gl_VertexIndex),
        float(gl_InstanceIndex),
        float(0x1234),
        float(0xcafe)
    );
}