void main() {
    // Initialize the vertex shader inputs to sensible default values.
    PostProcessVertexInputs inputs;
    initPostProcessMaterialVertex(inputs);

    inputs.normalizedUV = position.xy * 0.5 + 0.5;

    inputs.position = getPosition();

    // Invoke user code
    postProcessVertex(inputs);

    // (vertex domain) GL convention to inverted DX convention
    inputs.position.z = inputs.position.z * -0.5 + 0.5;

#if defined(TARGET_VULKAN_ENVIRONMENT)
    // In Vulkan, clip space is Y-down. In OpenGL, WebGPU and Metal, clip space is Y-up.
    inputs.position.y = -inputs.position.y;
#endif

    // Adjust clip-space
#if !defined(TARGET_VULKAN_ENVIRONMENT) && !defined(TARGET_METAL_ENVIRONMENT) && !defined(TARGET_WEBGPU_ENVIRONMENT)
    // This is not needed in Vulkan, Metal or WebGPU because clipControl is always (1, 0)
    // (We don't use a dot() here because it works around a spirv-opt optimization that in turn
    //  causes a crash on PowerVR, see #5118)
    inputs.position.z = inputs.position.z * frameUniforms.clipControl.x + inputs.position.w * frameUniforms.clipControl.y;
#endif

    // Handle user-defined interpolated attributes
#if defined(VARIABLE_CUSTOM0)
    VARIABLE_CUSTOM_AT0 = inputs.VARIABLE_CUSTOM0;
#endif
#if defined(VARIABLE_CUSTOM1)
    VARIABLE_CUSTOM_AT1 = inputs.VARIABLE_CUSTOM1;
#endif
#if defined(VARIABLE_CUSTOM2)
    VARIABLE_CUSTOM_AT2 = inputs.VARIABLE_CUSTOM2;
#endif
#if defined(VARIABLE_CUSTOM3)
    VARIABLE_CUSTOM_AT3 = inputs.VARIABLE_CUSTOM3;
#endif
#if defined(VARIABLE_CUSTOM4)
    VARIABLE_CUSTOM_AT4 = inputs.VARIABLE_CUSTOM4;
#endif

    // some PowerVR drivers crash when gl_Position is written more than once
    gl_Position = inputs.position;
}