120 lines
4.2 KiB
Plaintext
120 lines
4.2 KiB
Plaintext
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/*
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--------------------------------------------------------------------------------
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This source file is part of SkyX.
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Visit http://www.paradise-studios.net/products/skyx/
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Copyright (C) 2009-2012 Xavier Vergu<67>n Gonz<6E>lez <xavyiy@gmail.com>
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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Place - Suite 330, Boston, MA 02111-1307, USA, or go to
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http://www.gnu.org/copyleft/lesser.txt.
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--------------------------------------------------------------------------------
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*/
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// --------------------- SkyX skydome material ------------------------
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// ------------------------- GLSL Vertex ------------------------------
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// IN
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attribute vec4 vertex; // iPosition
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attribute vec3 uv0; // iNPosition
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attribute vec2 uv1; // iUV
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attribute float uv2; // iOpacity
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// OUT
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varying vec2 vUV;
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varying vec3 vRayleighColor;
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varying vec3 vMieColor;
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varying vec3 vDirection;
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varying float vOpacity;
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varying float vHeight;
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// UNIFORM
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// Global information
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uniform vec3 uLightDir;
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// Position information
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uniform vec3 uCameraPos;
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uniform vec3 uInvWaveLength;
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uniform float uInnerRadius;
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// Scattering parameters
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uniform float uKrESun; // Kr * ESun
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uniform float uKmESun; // Km * ESun
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uniform float uKr4PI; // Kr * 4 * PI
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uniform float uKm4PI; // Km * 4 * PI
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// Atmosphere properties
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uniform float uScale; // 1 / (outerRadius - innerRadius)
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uniform float uScaleDepth; // Where the average atmosphere density is found
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uniform float uScaleOverScaleDepth; // Scale / ScaleDepth
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// Number of samples
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uniform int uNumberOfSamples;
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uniform float uSamples;
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float scale(float cos, float uScaleDepth)
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{
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float x = 1.0 - cos;
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return uScaleDepth * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25))));
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}
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void main(void)
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{
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// Clip space position
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gl_Position = gl_ModelViewProjectionMatrix * vertex;
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vec3 v3Pos = uv0;
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v3Pos.y += uInnerRadius;
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vec3 v3Ray = v3Pos - uCameraPos;
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float fFar = length(v3Ray);
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v3Ray /= fFar;
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// Calculate the ray's starting position, then calculate its scattering offset
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vec3 v3Start = uCameraPos;
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float fHeight = uCameraPos.y;
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float fStartAngle = dot(v3Ray, v3Start) / fHeight;
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// NOTE: fDepth is not pased as parameter(like a constant) to avoid the little precission issue (Apreciable)
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float fDepth = exp(uScaleOverScaleDepth * (uInnerRadius - uCameraPos.y));
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float fStartOffset = fDepth * scale(fStartAngle, uScaleDepth);
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// Init loop variables
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float fSampleLength = fFar / uSamples;
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float fScaledLength = fSampleLength * uScale;
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vec3 v3SampleRay = v3Ray * fSampleLength;
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vec3 v3SamplePoint = v3Start + v3SampleRay * 0.5;
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// Loop the ray
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vec3 color = vec3(0,0,0);
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for (int i = 0; i < uNumberOfSamples; i++)
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{
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float fHeight = length(v3SamplePoint);
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float fDepth = exp(uScaleOverScaleDepth * (uInnerRadius-fHeight));
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float fLightAngle = dot(uLightDir, v3SamplePoint) / fHeight;
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float fCameraAngle = dot(v3Ray, v3SamplePoint) / fHeight;
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float fScatter = (fStartOffset + fDepth*(scale(fLightAngle, uScaleDepth) - scale(fCameraAngle, uScaleDepth)));
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vec3 v3Attenuate = exp(-fScatter * (uInvWaveLength * uKr4PI + uKm4PI)); // <<< TODO
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// Accumulate color
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v3Attenuate *= (fDepth * fScaledLength);
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color += v3Attenuate;
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// Next sample point
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v3SamplePoint += v3SampleRay;
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}
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// Outputs
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vRayleighColor = color * (uInvWaveLength * uKrESun); // TODO <--- parameter
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vMieColor = color * uKmESun; // TODO <--- *uInvMieWaveLength
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vDirection = uCameraPos - v3Pos;
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vUV = uv1;
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vOpacity = uv2;
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vHeight = 1.0-uv0.y;
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}
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