dali-toolkit/internal/controls/page-turn-view/page-turn-effect.cpp

   1 /*
   2  * Copyright (c) 2015 Samsung Electronics Co., Ltd.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  */
  17
  18 //EXTERNAL INCLUDES
  19 #include <string.h>
  20 #include <dali/public-api/animation/constraint.h>
  21 #include <dali/public-api/actors/actor.h>
  22 #include <dali/public-api/object/property-map.h>
  23
  24 //INTERNAL INCLUDES
  25 #include <dali-toolkit/internal/controls/page-turn-view/page-turn-effect.h>
  26
  27 using namespace Dali;
  28 using namespace Dali::Toolkit;
  29
  30 namespace
  31 {
  32 #define DALI_COMPOSE_SHADER(STR) #STR
  33 const char * const PROPERTY_COMMON_PARAMETERS( "uCommonParameters" );
  34 const char * const PROPERTY_ORIGINAL_CENTER( "originalCenter" );
  35 const char * const PROPERTY_CURRENT_CENTER( "currentCenter" );
  36 }
  37
  38 /**
  39  * This constraint updates the common parameter values used by every vertex.
  40  * By using constraint, they are calculate once in CPU then pass into the vertex shader as uniforms
  41  */
  42 struct CommonParametersConstraint
  43 {
  44   CommonParametersConstraint( float pageHeight )
  45   : mPageHeight( pageHeight )
  46   {}
  47
  48   void operator()( Dali::Matrix& current, const PropertyInputContainer& inputs )
  49   {
  50     const Vector2& originalCenter = inputs[0]->GetVector2();
  51     Vector2 currentCenter = inputs[1]->GetVector2();
  52
  53     // calculate the curve direction and the vanishing point
  54     // here, the vanishing point is the intersection of spine with the line passing through original center and vertical to curve direction
  55     Vector2 curveDirection( currentCenter - originalCenter );
  56     curveDirection.Normalize();
  57     if( fabs(curveDirection.y) < 0.01f) // eliminate the possibility of division by zero in the next step
  58     {
  59       curveDirection.y = 0.01f;
  60     }
  61     float vanishingPointY = originalCenter.y + curveDirection.x * originalCenter.x / curveDirection.y;
  62
  63     float curveEndY, cosTheta ,sinTheta ,translateX, translateY;
  64     // when the vanishing point is very far away, make it infinitely, in this case, the page bent horizontally
  65     const float THRESHOLD(20.0);
  66     if( fabs(vanishingPointY-mPageHeight*0.5f) >= mPageHeight*THRESHOLD )
  67     {
  68       curveDirection = Vector2(-1.f,0.f);
  69       currentCenter.y = originalCenter.y;
  70
  71       curveEndY = originalCenter.y;
  72       cosTheta = 1.f;
  73       sinTheta = 0.f;
  74       translateX = currentCenter.x - originalCenter.x;
  75       translateY = vanishingPointY;
  76     }
  77     else
  78     {
  79       curveEndY = currentCenter.y - curveDirection.y * (currentCenter.x/curveDirection.x) ;
  80       Vector2 v1( currentCenter.x, currentCenter.y - vanishingPointY );
  81       v1.Normalize();
  82       Vector2 v2( originalCenter.x, originalCenter.y - vanishingPointY );
  83       v2.Normalize();
  84       cosTheta = v1.x*v2.x + v1.y*v2.y;
  85       sinTheta = ( vanishingPointY > mPageHeight*0.5f ) ? sqrt(1.0-cosTheta*cosTheta) : -sqrt(1.0-cosTheta*cosTheta);
  86       translateX = currentCenter.x - cosTheta*originalCenter.x - sinTheta*( originalCenter.y-vanishingPointY );
  87       translateY = currentCenter.y + sinTheta*originalCenter.x - cosTheta*( originalCenter.y-vanishingPointY );
  88     }
  89
  90     float originalLength = fabs(originalCenter.x/curveDirection.x);
  91     float currentLength = fabs(currentCenter.x/curveDirection.x);
  92     float curveHeight = 0.45f*sqrt(originalLength*originalLength - currentLength*currentLength);
  93
  94     float* parameterArray = current.AsFloat();
  95     parameterArray[0] = cosTheta;
  96     parameterArray[1] = -sinTheta;
  97     parameterArray[2] = originalCenter.x;
  98     parameterArray[3] = originalCenter.y;
  99     parameterArray[4] = sinTheta;
 100     parameterArray[5] = cosTheta;
 101     parameterArray[6] = currentCenter.x;
 102     parameterArray[7] = currentCenter.y;
 103     parameterArray[8] = translateX;
 104     parameterArray[9] = translateY;
 105     parameterArray[10] = vanishingPointY;
 106     parameterArray[11] = curveEndY;
 107     parameterArray[12] = curveDirection.x;
 108     parameterArray[13] = curveDirection.y;
 109     parameterArray[14] = curveHeight;
 110     parameterArray[15] = currentLength;
 111   }
 112
 113   float mPageHeight;
 114 };
 115
 116 void Dali::Toolkit::Internal::PageTurnApplyInternalConstraint( Actor& actor, float pageHeight )
 117 {
 118   Constraint constraint = Constraint::New<Dali::Matrix>( actor, actor.GetPropertyIndex( PROPERTY_COMMON_PARAMETERS ) , CommonParametersConstraint( pageHeight ) );
 119   constraint.AddSource( LocalSource( actor.GetPropertyIndex( PROPERTY_ORIGINAL_CENTER ) ) );
 120   constraint.AddSource( LocalSource( actor.GetPropertyIndex( PROPERTY_CURRENT_CENTER ) ) );
 121   constraint.Apply();
 122 }
 123
 124 Property::Map Dali::Toolkit::Internal::CreatePageTurnEffect()
 125 {
 126   const char* vertexShader = DALI_COMPOSE_SHADER(
 127       /*
 128        * The common parameters for all the vertices, calculate in CPU then pass into the shader as uniforms
 129        *
 130        *  first part of the page, (outside the the line passing through original center and vertical to curve direction)
 131        * no Z change, only 2D rotation and translation
 132        * ([0][0],[0][1],[1][0],[1][1]) mat2 rotateMatrix
 133        * ([2][0],[2][1]) vec2 translationVector
 134        *
 135        * ([0][2],[0][3]) vec2 originalCenter: Typically the press down position of the Pan Gesture
 136        * ([1][2],[1][3]) vec2 currentCenter: Typically the current position of the Pan Gesture
 137        * ([3][0],[3][1]) vec2 curveDirection: The normalized vector pointing from original center to current center
 138        * ([2][2]) float vanishingPointY: The Y coordinate of the intersection of the spine
 139        *                                 and the line which goes through the original center and is vertical to the curveDirection
 140        * ([2][3]) float curveEndY: The Y coordinate of intersection of the spine and the line through both original and current center
 141        * ([3][2]) float curveHeight: The height of the interpolated hermite curve.
 142        * ([3][3]) float currentLength: The length from the current center to the curveEnd.
 143        */
 144       precision mediump float;\n
 145       \n
 146       attribute mediump vec2 aPosition;\n
 147       \n
 148       uniform mediump mat4 uMvpMatrix;\n
 149       uniform mediump mat3 uNormalMatrix;\n
 150       uniform mediump mat4 uModelView;\n
 151       \n
 152       uniform mat4 uCommonParameters;\n
 153       \n
 154       uniform vec3 uSize;\n
 155       uniform float uIsTurningBack;\n
 156       uniform float uTextureWidth;\n
 157       varying vec3 vNormal;\n
 158       varying vec4 vPosition;\n
 159       varying mediump vec2 vTexCoord;\n
 160       \n
 161       void main()\n
 162       {\n
 163         vec4 position = vec4( aPosition*uSize.xy, 0.0, 1.0);\n
 164         vec2 currentCenter = vec2( uCommonParameters[1][2], uCommonParameters[1][3]);\n
 165         vec2 originalCenter = vec2( uCommonParameters[0][2], uCommonParameters[0][3]);\n
 166         vec3 normal = vec3(0.0,0.0,1.0);\n
 167         \n
 168         if(currentCenter.x < originalCenter.x)\n
 169         {\n
 170           // change the coordinate origin from the center of the page to its top-left
 171           position.xy += uSize.xy * 0.5;\n
 172           vec2 curveDirection = vec2( uCommonParameters[3]);\n
 173           vec3 vanishingPoint = vec3(0.0, uCommonParameters[2][2], 0.0);\n
 174           // first part of the page, (outside the the line passing through original center and vertical to curve direction)
 175           //no Z change, only 2D rotation and translation
 176           if( dot(curveDirection, position.xy - originalCenter) < 0.0 )
 177           {\n
 178             position.y -= vanishingPoint.y;\n
 179             position.xy = mat2(uCommonParameters)*position.xy + vec2( uCommonParameters[2]);\n
 180           }\n
 181           // second part of the page, bent as a ruled surface
 182           else\n
 183           {\n
 184             // calculate on the flat plane, between
 185             // the first line passing through current vertex and vanishing point
 186             // the second line passing through original center and current center
 187             vec2 curveEnd = vec2( 0.0, uCommonParameters[2][3] );\n
 188             vec2 curFlatDirection = vec2(0.0,1.0);\n
 189             float lengthFromCurve = position.y - originalCenter.y;\n
 190             float lengthOnCurve = position.x;\n
 191             if(currentCenter.y != originalCenter.y)\n
 192             {\n
 193               curFlatDirection = normalize(position.xy - vanishingPoint.xy);\n
 194               lengthFromCurve = (curveEnd.x*curveDirection.y-curveEnd.y*curveDirection.x-position.x*curveDirection.y+position.y*curveDirection.x)
 195               / (curFlatDirection.x*curveDirection.y-curFlatDirection.y*curveDirection.x);\n
 196               lengthOnCurve = length(position.xy+lengthFromCurve*curFlatDirection-curveEnd);\n
 197             }\n
 198             \n
 199             // define the control points of hermite curve, composed with two segments
 200             // calculation is carried out on the 2D plane which is passing through both current and original center and vertical to the image plane
 201             float currentLength = uCommonParameters[3][3];\n
 202             float originalLength =  abs(originalCenter.x/curveDirection.x);\n
 203             float height = uCommonParameters[3][2];\n
 204             float percentage = currentLength/originalLength;\n
 205             //vec2 SegmentOneControlPoint0 = vec2(0.0, 0.0);
 206             vec2 SegmentOneControlPoint1 = vec2((0.65*percentage - 0.15)*originalLength, (0.8 + 0.2 * percentage)*height); \n
 207             vec2 SegmentTwoControlPoint0 = SegmentOneControlPoint1;\n
 208             vec2 SegmentTwoControlPoint1 = vec2(currentLength, 0.0); \n
 209             vec2 SegmentOneTangentVector0 = SegmentOneControlPoint1;\n
 210             vec2 SegmentOneTangentVector1 = vec2(0.5*originalLength,0.0);\n
 211             vec2 SegmentTwoTangentVector0 = SegmentOneTangentVector1;\n
 212             vec2 SegmentTwoTangentVector1 = SegmentOneTangentVector1;\n
 213             \n
 214             // calculate the corresponding curve point position and its tangent vector
 215             // it is a linear mapping onto nonlinear curves, might cause some unwanted deformation
 216             // but as there are no analytical method to calculate the curve length on arbitrary segment
 217             // no efficient way to solve this nonlinear mapping, Numerical approximation would cost too much computation in shader
 218             vec2 curvePoint2D;\n
 219             vec2 tangent;\n
 220             float t0 = lengthOnCurve / originalLength;\n
 221             if(t0<=0.5)\n
 222             {\n
 223               float t = 2.0*t0;\n
 224               float t_2 = t*t;\n
 225               float t_3 = t*t_2;\n
 226               curvePoint2D = (-2.0*t_3+3.0*t_2)*SegmentOneControlPoint1
 227               + (t_3-2.0*t_2+t)*SegmentOneTangentVector0 + (t_3-t_2)*SegmentOneTangentVector1;\n
 228               tangent = (-6.0*t_2+6.0*t)*SegmentOneControlPoint1
 229               + (3.0*t_2-4.0*t+1.0)*SegmentOneTangentVector0 + (3.0*t_2-2.0*t)*SegmentOneTangentVector1;\n
 230             }\n
 231             else\n
 232             {\n
 233               float t = 2.0*t0-1.0;\n
 234               float t_2 = t*t;\n
 235               float t_3 = t*t_2;\n
 236               curvePoint2D = (2.0*t_3-3.0*t_2+1.0)*SegmentTwoControlPoint0 + (-2.0*t_3+3.0*t_2)*SegmentTwoControlPoint1
 237               + (t_3-2.0*t_2+t)*SegmentTwoTangentVector0 + (t_3-t_2)*SegmentTwoTangentVector1;\n
 238               tangent = (6.0*t_2-6.0*t)*SegmentTwoControlPoint0 + (-6.0*t_2+6.0*t)*SegmentTwoControlPoint1
 239               + (3.0*t_2-4.0*t+1.0)*SegmentTwoTangentVector0 + (3.0*t_2-2.0*t)*SegmentTwoTangentVector1;\n
 240               // a trick to eliminate some optical illusion caused by the gradient matter of normal in per-fragment shading
 241               // which is caused by linear interpolation of normal vs. nonlinear lighting
 242               // will notice some artifact in the areas with dramatically normal changes, so compress the normal differences here
 243               tangent.y *=  min(1.0, length(position.xyz - vanishingPoint) / uSize.y ); \n
 244             }\n
 245             vec3 curvePoint = vec3(curveEnd - curvePoint2D.x*curveDirection,max(0.0,curvePoint2D.y));\n
 246             vec3 tangentVector = vec3(-tangent.x*curveDirection,tangent.y);\n
 247             \n
 248             // locate the new vertex position on the line passing through both vanishing point and the calculated curve point position
 249             vec3 curLiftDirection = vec3(0.0,-1.0,0.0);\n
 250             if(currentCenter.y != originalCenter.y)\n
 251             {\n
 252               curLiftDirection = normalize(curvePoint - vanishingPoint);\n
 253               tangentVector *= (curveDirection.y > 0.0) ? -1.0 : 1.0;\n
 254               // an heuristic adjustment here, to compensate the linear parameter mapping onto the nonlinear curve
 255               float Y0 = position.y - curveDirection.y * (position.x/curveDirection.x); \n
 256               float proportion;
 257               float refLength;\n
 258               if(abs(Y0-vanishingPoint.y) > abs(curveEnd.y-vanishingPoint.y)) \n
 259               {\n
 260                 proportion = abs(curveEnd.y - Y0) / (abs(curveEnd.y-Y0)+abs(curveEnd.y - vanishingPoint.y)); \n
 261                 refLength = proportion*length(originalCenter-vanishingPoint.xy) / (proportion-1.0); \n
 262               }\n
 263               else\n
 264               {\n
 265                 proportion = abs(curveEnd.y - Y0) / abs(curveEnd.y - vanishingPoint.y);\n
 266                 refLength = proportion*length(originalCenter-vanishingPoint.xy); \n
 267               }\n
 268               float Y1 = currentCenter.y - (normalize(currentCenter-vanishingPoint.xy)).y * refLength; \n
 269               position.y = mix(Y0, Y1, t0); \n
 270             }\n
 271             position.xz = curvePoint.xz - lengthFromCurve*curLiftDirection.xz;\n
 272             // calculate the normal vector, will be used for lighting
 273             normal = cross(curLiftDirection, normalize(tangentVector));\n
 274             // the signature of Z is decided by the page turning direction:
 275             // from left to right(negative); from right to left (positive)
 276             position.z *= -uIsTurningBack;\n
 277             normal.xy *= -uIsTurningBack;\n
 278           }\n
 279           // change the coordinate origin from the top-left of the page to its center
 280           position.xy -= uSize.xy * 0.5; \n
 281         }\n
 282         vNormal =  uNormalMatrix * normal;\n
 283         gl_Position = uMvpMatrix * position;
 284         // varying parameters for fragment shader
 285         vTexCoord = aPosition + vec2(0.5);\n
 286         vTexCoord.x /= uTextureWidth;
 287         vPosition = uModelView * position;\n
 288       }\n
 289   );
 290
 291   const char* fragmentShader = DALI_COMPOSE_SHADER(
 292       precision mediump float;\n
 293       \n
 294       varying mediump vec2 vTexCoord;\n
 295       \n
 296       uniform sampler2D sTexture;\n
 297       uniform lowp vec4 uColor;\n
 298       uniform vec3 uSize;\n
 299       uniform vec2 uSpineShadowParameter;\n
 300       varying vec3 vNormal;\n
 301       varying vec4 vPosition;\n
 302       \n
 303       void main()\n
 304       {\n
 305         // need to re-normalize the interpolated normal
 306         vec3 normal = normalize( vNormal );\n
 307         // display page content
 308         vec4 texel;
 309         // display back image of the page, flip the texture
 310         if(  dot(vPosition.xyz, normal) > 0.0 ) texel = texture2D( sTexture, vec2( 1.0 - vTexCoord.x, vTexCoord.y ) );\n
 311         // display front image of the page
 312         else texel = texture2D( sTexture, vTexCoord );\n
 313
 314         // display book spine, a stripe of shadowed texture
 315         float pixelPos = vTexCoord.x * uSize.x; \n
 316         float spineShadowCoef = 1.0; \n
 317         if( pixelPos < uSpineShadowParameter.x ) \n
 318         {\n
 319           float x = pixelPos - uSpineShadowParameter.x;\n
 320           float y = sqrt( uSpineShadowParameter.x*uSpineShadowParameter.x - x*x );\n
 321           spineShadowCoef = normalize( vec2( uSpineShadowParameter.y*x/uSpineShadowParameter.x, y ) ).y;\n
 322         }\n
 323         // calculate the lighting
 324         // set the ambient color as vec3(0.4);
 325         float lightColor = abs( normal.z ) * 0.6 + 0.4;\n
 326         gl_FragColor = vec4( ( spineShadowCoef * lightColor ) * texel.rgb , texel.a ) * uColor;\n
 327       }
 328   );
 329
 330   Property::Map map;
 331
 332   Property::Map customShader;
 333
 334   customShader[ "vertexShader" ] = vertexShader;
 335   customShader[ "fragmentShader" ] = fragmentShader;
 336   customShader[ "subdivideGridX" ] = 20;
 337   customShader[ "subdivideGridY" ] = 20;
 338
 339   map[ "shader" ] = customShader;
 340   return map;
 341
 342 }
 343