/*

 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#include <simd/simd.h>

#include <metal_stdlib>

#include "common.h"

using namespace metal;

struct VertexInput {

    float3 position [[attribute(VertexAttributePosition)]];

};

struct TxtVertexInput {

    float3 position [[attribute(VertexAttributePosition)]];

    float2 texCoords [[attribute(VertexAttributeTexPos)]];

};

struct ColShaderInOut {

    float4 position [[position]];

    half4  color;

};

struct TxtShaderInOut {

    float4 position [[position]];

    float2 texCoords;

};

struct GradShaderInOut {

    float4 position [[position]];

};

vertex ColShaderInOut vert_col(VertexInput in [[stage_in]],

	   constant FrameUniforms& uniforms [[buffer(FrameUniformBuffer)]],

       constant TransformMatrix& transform [[buffer(MatrixBuffer)]]) {

    ColShaderInOut out;

    float4 pos4 = float4(in.position, 1.0);

    out.position = transform.transformMatrix*pos4;

    out.color = half4(uniforms.color.r, uniforms.color.g, uniforms.color.b, uniforms.color.a);

    return out;

}

vertex GradShaderInOut vert_grad(VertexInput in [[stage_in]], constant TransformMatrix& transform [[buffer(MatrixBuffer)]]) {

    GradShaderInOut out;

    float4 pos4 = float4(in.position, 1.0);

    out.position = transform.transformMatrix*pos4;

    return out;

}

vertex TxtShaderInOut vert_txt(TxtVertexInput in [[stage_in]], constant TransformMatrix& transform [[buffer(MatrixBuffer)]]) {

    TxtShaderInOut out;

    float4 pos4 = float4(in.position, 1.0);

    out.position = transform.transformMatrix*pos4;

    out.texCoords = in.texCoords;

    return out;

}

fragment half4 frag_col(ColShaderInOut in [[stage_in]]) {

    return in.color;

}

fragment half4 frag_txt(

        TxtShaderInOut vert [[stage_in]],

        texture2d<float, access::sample> renderTexture [[texture(0)]]

        )

{

    constexpr sampler textureSampler (mag_filter::linear,

                                  min_filter::linear);

    float4 pixelColor = renderTexture.sample(textureSampler, vert.texCoords);

    return half4(pixelColor.r, pixelColor.g, pixelColor.b , pixelColor.a);

}

fragment half4 frag_grad(GradShaderInOut in [[stage_in]],

                         constant GradFrameUniforms& uniforms [[buffer(0)]]) {

    float3 v = float3(in.position.x, in.position.y, 1);

    float  a = (dot(v,uniforms.params)-0.25)*2.0;

    float4 c = mix(uniforms.color1, uniforms.color2, a);

    return half4(c);

}