<@include gpu/Config.slh@>
<$VERSION_HEADER$>
//
//  Add outline effect based on two zbuffers : one containing the total scene z and another 
//  with the z of only the objects to be outlined
//
//  Created by Olivier Prat on 08/09/2017
//  Copyright 2017 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
<@include DeferredTransform.slh@>
<$declareDeferredFrameTransform()$>

<@include Outline_shared.slh@>

uniform outlineParamsBuffer {
	OutlineParameters params;
};

uniform sampler2D sceneDepthMap;
uniform sampler2D outlinedDepthMap;

in vec2 varTexCoord0;
out vec4 outFragColor;

const float FAR_Z = 1.0;
const float LINEAR_DEPTH_BIAS = 5e-3;
const float OPACITY_EPSILON = 5e-3;

void main(void) {
	float outlinedDepth = texture(outlinedDepthMap, varTexCoord0).x;
    float intensity = 0.0;

    if (outlinedDepth < FAR_Z) {
        // We're not on the far plane so we are on the outlined object, thus no outline to do!

        // But maybe we need to fill the interior
        // TODO: this should be done as another shader with switch done on CPU
        if (params._fillOpacityUnoccluded>OPACITY_EPSILON && params._fillOpacityUnoccluded>OPACITY_EPSILON) {
            float sceneDepth = texture(sceneDepthMap, varTexCoord0).x;
            // Transform to linear depth for better precision
            outlinedDepth = -evalZeyeFromZdb(outlinedDepth);
            sceneDepth = -evalZeyeFromZdb(sceneDepth);

            // Are we occluded?
            if (sceneDepth < (outlinedDepth-LINEAR_DEPTH_BIAS)) {
                intensity = params._fillOpacityOccluded;
            } else {
                intensity = params._fillOpacityUnoccluded;
            }
        } else {
            discard;
        }
    } else {
        float weight = 0.0;
        vec2 deltaUv = params._size / params._blurKernelSize;
        vec2 lineStartUv = varTexCoord0 - params._size / 2.0; 
        vec2 uv;
        int x;
        int y;

        for (y=0 ; y<params._blurKernelSize ; y++) {
            uv = lineStartUv;
            lineStartUv.y += deltaUv.y;

            if (uv.y>=0.0 && uv.y<=1.0) {
                for (x=0 ; x<params._blurKernelSize ; x++) {
                    if (uv.x>=0.0 && uv.x<=1.0)
                    {
                        outlinedDepth = texture(outlinedDepthMap, uv).x;
                        intensity += (outlinedDepth < FAR_Z) ? 1.0 : 0.0;
                        weight += 1.f;
                    }
                    uv.x += deltaUv.x;
                }
            }
        }

        intensity /= weight;
        if (intensity < OPACITY_EPSILON) {
            discard;
        }

        intensity = min(1.0, intensity / params._threshold) * params._intensity;
    }

	outFragColor = vec4(params._color.rgb, intensity);
}