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/**
* @file class3/deferred/screenSpaceReflUtil.glsl
*
* $LicenseInfo:firstyear=2007&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2007, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
uniform sampler2D depthMap;
uniform sampler2D normalMap;
uniform sampler2D sceneMap;
uniform vec2 screen_res;
uniform mat4 projection_matrix;
uniform float zNear;
uniform float zFar;
uniform mat4 inv_proj;
vec4 getPositionWithDepth(vec2 pos_screen, float depth);
float linearDepth(float depth, float near, float far);
float getDepth(vec2 pos_screen);
float linearDepth01(float d, float znear, float zfar);
float random (vec2 uv) {
return fract(sin(dot(uv, vec2(12.9898, 78.233))) * 43758.5453123); //simple random function
}
// Based off of https://github.com/RoundedGlint585/ScreenSpaceReflection/
// A few tweaks here and there to suit our needs.
vec2 generateProjectedPosition(vec3 pos){
vec4 samplePosition = projection_matrix * vec4(pos, 1.f);
samplePosition.xy = (samplePosition.xy / samplePosition.w) * 0.5 + 0.5;
return samplePosition.xy;
}
bool isBinarySearchEnabled = true;
bool isAdaptiveStepEnabled = true;
bool isExponentialStepEnabled = false;
bool debugDraw = false;
int iterationCount = 100;
float rayStep = 0.2;
float distanceBias = 0.05;
float depthRejectBias = 0.001;
float epsilon = 0.1;
bool traceScreenRay(vec3 position, vec3 reflection, out vec3 hitColor, out float hitDepth, float depth, sampler2D textureFrame) {
vec3 step = rayStep * reflection;
vec3 marchingPosition = position + step;
float delta;
float depthFromScreen;
vec2 screenPosition;
bool hit = false;
hitColor = vec3(0);
int i = 0;
if (depth > depthRejectBias) {
for (; i < iterationCount && !hit; i++) {
screenPosition = generateProjectedPosition(marchingPosition);
depthFromScreen = abs(getPositionWithDepth(screenPosition, linearDepth(getDepth(screenPosition), zNear, zFar)).z);
delta = abs(marchingPosition.z) - depthFromScreen;
if (depth < depthFromScreen + epsilon && depth > depthFromScreen - epsilon) {
break;
}
if (abs(delta) < distanceBias) {
vec3 color = vec3(1);
if(debugDraw)
color = vec3( 0.5+ sign(delta)/2,0.3,0.5- sign(delta)/2);
hitColor = texture(textureFrame, screenPosition).xyz * color;
hitDepth = depthFromScreen;
hit = true;
break;
}
if (isBinarySearchEnabled && delta > 0) {
break;
}
if (isAdaptiveStepEnabled){
float directionSign = sign(abs(marchingPosition.z) - depthFromScreen);
//this is sort of adapting step, should prevent lining reflection by doing sort of iterative converging
//some implementation doing it by binary search, but I found this idea more cheaty and way easier to implement
step = step * (1.0 - rayStep * max(directionSign, 0.0));
marchingPosition += step * (-directionSign);
}
else {
marchingPosition += step;
}
if (isExponentialStepEnabled){
step *= 1.05;
}
}
if(isBinarySearchEnabled){
for(; i < iterationCount && !hit; i++){
step *= 0.5;
marchingPosition = marchingPosition - step * sign(delta);
screenPosition = generateProjectedPosition(marchingPosition);
depthFromScreen = abs(getPositionWithDepth(screenPosition, getDepth(screenPosition)).z);
delta = abs(marchingPosition.z) - depthFromScreen;
if (depth < depthFromScreen + epsilon && depth > depthFromScreen - epsilon) {
break;
}
if (abs(delta) < distanceBias && depthFromScreen != (depth - distanceBias)) {
vec3 color = vec3(1);
if(debugDraw)
color = vec3( 0.5+ sign(delta)/2,0.3,0.5- sign(delta)/2);
hitColor = texture(textureFrame, screenPosition).xyz * color;
hitDepth = depthFromScreen;
hit = true;
break;
}
}
}
}
return hit;
}
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