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library / src / main / res / raw / main_vertex_shader.glsl @ 1e667536

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//////////////////////////////////////////////////////////////////////////////////////////////
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// Copyright 2016 Leszek Koltunski                                                          //
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//                                                                                          //
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// This file is part of Distorted.                                                          //
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//                                                                                          //
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// Distorted is free software: you can redistribute it and/or modify                        //
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// it under the terms of the GNU General Public License as published by                     //
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// the Free Software Foundation, either version 2 of the License, or                        //
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// (at your option) any later version.                                                      //
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//                                                                                          //
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// Distorted is distributed in the hope that it will be useful,                             //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of                           //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                            //
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// GNU General Public License for more details.                                             //
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//                                                                                          //
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// You should have received a copy of the GNU General Public License                        // 
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// along with Distorted.  If not, see <http://www.gnu.org/licenses/>.                       //
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//////////////////////////////////////////////////////////////////////////////////////////////
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precision highp float;
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precision highp int;
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in vec3 a_Position;                  // Per-vertex position.
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in vec3 a_Normal;                    // Per-vertex normal vector.
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in vec3 a_Inflate;                   // This vector describes the direction this vertex needs to go when we 'inflate' the whole mesh.
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                                     // If the mesh is locally smooth, this is equal to the normal vector. Otherwise (on sharp edges) - no.
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in vec2 a_TexCoordinate;             // Per-vertex texture coordinate.
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in float a_Association;              // Per-vertex association. Connects the vertex (really the mesh component the vertex is a member of)
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                                     // to a vertex effect. An effect will only be active on a vertex iff (a_Association & vAssociation[effect]) != 0.
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                                     // ( see VertexEffect.retSection() )
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out vec3 v_Position;                 //
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out vec3 v_endPosition;              // for Transform Feedback only
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#ifdef PREAPPLY
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out vec3 v_Inflate;                  // Transform Feedback for preapply effects
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#endif
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out vec3 v_Normal;                   //
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out vec2 v_TexCoordinate;            //
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uniform mat4 u_MVPMatrix;            // the combined model/view/projection matrix.
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uniform mat4 u_MVMatrix;             // the combined model/view matrix.
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uniform float u_Inflate;             // how much should we inflate (>0.0) or deflate (<0.0) the mesh.
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#if NUM_VERTEX>0
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uniform int vNumEffects;             // total number of vertex effects
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uniform int vName[NUM_VERTEX];       // their names.
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uniform vec4 vUniforms[3*NUM_VERTEX];// i-th effect is 3 consecutive vec4's: [3*i], [3*i+1], [3*i+2].
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                                     // The first vec4 is the Interpolated values,
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                                     // second vec4: first float - cache, next 3: Center, the third -  the Region.
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uniform int vAssociation[NUM_VERTEX];// Associations of the vertex effects. Those are used to connect an effect to a Mesh component.
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//////////////////////////////////////////////////////////////////////////////////////////////
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// HELPER FUNCTIONS
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//////////////////////////////////////////////////////////////////////////////////////////////
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// Return degree of the point as defined by the Region. Currently only supports spherical regions.
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//
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// Let 'PS' be the vector from point P (the current vertex) to point S (the center of the effect).
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// Let region.xyz be the vector from point S to point O (the center point of the region sphere)
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// Let region.w be the radius of the region sphere.
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// (This all should work regardless if S is inside or outside of the sphere).
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//
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// Then, the degree of a point with respect to a given (spherical!) Region is defined by:
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//
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// If P is outside the sphere, return 0.
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// Otherwise, let X be the point where the halfline SP meets the sphere - then return |PX|/|SX|,
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// aka the 'degree' of point P.
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//
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// We solve the triangle OPX.
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// We know the lengths |PO|, |OX| and the angle OPX, because cos(OPX) = cos(180-OPS) = -cos(OPS) = -PS*PO/(|PS|*|PO|)
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// then from the law of cosines PX^2 + PO^2 - 2*PX*PO*cos(OPX) = OX^2 so PX = -a + sqrt(a^2 + OX^2 - PO^2)
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// where a = PS*PO/|PS| but we are really looking for d = |PX|/(|PX|+|PS|) = 1/(1+ (|PS|/|PX|) ) and
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// |PX|/|PS| = -b + sqrt(b^2 + (OX^2-PO^2)/PS^2) where b=PS*PO/|PS|^2 which can be computed with only one sqrt.
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float degree(in vec4 region, in vec3 PS)
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  {
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  float ps_sq = dot(PS,PS);
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  if( ps_sq==0.0 ) return 1.0;
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  vec3 PO = PS + region.xyz;
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  float d = region.w*region.w-dot(PO,PO);
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  if( d<=0.0 ) return 0.0;
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  float b = dot(PS,PO)/ps_sq;
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  return 1.0 / (1.0 + 1.0/(sqrt(b*b + d/ps_sq)-b));
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  }
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#endif  // NUM_VERTEX>0
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//////////////////////////////////////////////////////////////////////////////////////////////
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void main()
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  {
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  vec3 v = a_Position + u_Inflate*a_Inflate;
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  vec3 n = a_Normal;
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#ifdef PREAPPLY
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  vec3 inf = a_Inflate;
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#endif
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#if NUM_VERTEX>0
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  int effect=0;
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  for(int i=0; i<vNumEffects; i++)
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    {
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    // ENABLED EFFECTS WILL BE INSERTED HERE
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    effect+=3;
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    }
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#endif
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  v_Position      = v;
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#ifdef PREAPPLY
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  v_endPosition   = n;
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  v_Inflate       = inf;
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#else
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  v_endPosition   = v + 0.5*n;
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#endif
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  v_TexCoordinate = a_TexCoordinate;
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  v_Normal        = normalize(vec3(u_MVMatrix*vec4(n,0.0)));
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  gl_Position     = u_MVPMatrix*vec4(v,1.0);
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  }