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<head>
<meta name="viewport" content="width=600">
<meta http-equiv="Content-type" content="text/html; charset=utf-8">
<title>WebMetal Cubes demo</title>
<link rel="stylesheet" href="shared.css">
<link rel="stylesheet" href="https://webkit.org/wp-content/themes/webkit/style.css">
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<script src="gl-matrix-min.js"></script>
<script src="shared.js"></script>
<script src="cubes.js"></script>
<script id="library" type="x-shader/x-metal">
#include <metal_stdlib>
#include <simd/simd.h>

using namespace metal;

struct uniform_t
{
    float4x4 modelview_projection_matrix;
    float4x4 normal_matrix;
    float4 ambient_color;
    float multiplier;
} __attribute__ ((aligned (256)));

constant float3 light_position = float3(0.0, -1.0, 1.0);
constant float4 light_color = float4(1, 1, 1, 1);

struct vertex_t
{
    packed_float3 position;
    packed_float3 normal;
};

struct varying_t {
    float4 position [[position]];
    half4 color;
};

vertex varying_t vertex_function(device vertex_t* vertex_array [[ buffer(0) ]],
                               constant uniform_t& uniforms [[ buffer(1) ]],
                               unsigned int vid [[ vertex_id ]])
{
    varying_t out;

    float4 position = float4(float3(vertex_array[vid].position), 1.0);
    out.position = uniforms.modelview_projection_matrix * position;

    float3 normal = vertex_array[vid].normal;
    float4 eye_normal = normalize(uniforms.normal_matrix * float4(normal, 0.0));

    float n_dot_l = dot(eye_normal.rgb, normalize(light_position));
    n_dot_l = fmax(0.0, n_dot_l);

    out.color = half4(uniforms.ambient_color + light_color * n_dot_l);

    return out;
}

fragment half4 fragment_function(varying_t in [[stage_in]])
{
    return in.color;
};
</script>
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<div id="error">
    <h2>WebMetal not available</h2>
    <p>
        Make sure you are on a system with WebMetal enabled. In
        Safari, first make sure the Developer Menu is visible (Preferences →
        Advanced), then Develop → Experimental Features → Enable WebMetal.
    </p>
</div>
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