2 // Copyright (c) 2014 Samsung Electronics Co., Ltd.
4 // Licensed under the Flora License, Version 1.0 (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
8 // http://floralicense.org/license/
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.
17 #include <dali-toolkit/public-api/shader-effects/motion-stretch-effect.h>
27 struct MatrixFromPropertiesConstraint
29 MatrixFromPropertiesConstraint()
33 Matrix operator()( const Matrix& current,
34 const PropertyInput& propertyPosition,
35 const PropertyInput& propertyOrientation,
36 const PropertyInput& propertyScale )
39 mat4.SetTransformComponents( propertyScale.GetVector3(),
40 propertyOrientation.GetQuaternion(),
41 propertyPosition.GetVector3() );
47 const std::string MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME( "uGeometryStretchFactor" );
48 const std::string MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME( "uSpeedScalingFactor" );
49 const std::string MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME( "uObjectFadeStart" );
50 const std::string MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME( "uObjectFadeEnd" );
51 const std::string MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME( "uAlphaScale" );
52 const std::string MOTION_STRETCH_MODELVIEW_LASTFRAME( "uModelLastFrame" ); ///< Matrix
54 ////////////////////////////////////////////////////
56 // Motion stretch shader / actor tweaking parameters
59 // half width and half height respectively of actor, corresponding to values in vertex attribute stream
60 // Note that these values work for normal image actor (verts +/- 0.5) but a grid or a nine square seemsi
61 // to have verts in pixel space (e.g. 256,256). Need to fix this somehow,
62 // either in Dali or by passing uniforms which we can use to 'normalise' the verts in the vertex shader
63 const Vector2 MOTION_STRETCH_ACTOR_VERTEX( 0.5f, 0.5f );
65 const float MOTION_STRETCH_GEOM_STRETCH_SCALING_FACTOR = 0.5f; // scaling factor for how much to stretch actor geom as it moves
66 const float MOTION_STRETCH_SPEED_SCALING_FACTOR = 0.5f; // scales the speed, producing a number affecting how much the actor stretches & fades at the edges
68 const Vector2 MOTION_STRETCH_OBJECT_FADE_END( MOTION_STRETCH_ACTOR_VERTEX ); // displacement from center at which actor fully fades to zero alpha
69 const Vector2 MOTION_STRETCH_OBJECT_FADE_START( MOTION_STRETCH_OBJECT_FADE_END * 0.5f ); // displacement from center at which actor start to fade from full alpha
71 const float MOTION_STRETCH_ALPHA_SCALE = 0.75f; // global scaler applied to actor alpha as it is stretched + moving
76 MotionStretchEffect::MotionStretchEffect()
80 // Call the Parent copy constructor to add reference to the implementation for this object
81 MotionStretchEffect::MotionStretchEffect( ShaderEffect handle )
82 :ShaderEffect( handle )
86 MotionStretchEffect::~MotionStretchEffect()
90 MotionStretchEffect MotionStretchEffect::Apply( Actor handle )
92 MotionStretchEffect newEffect = New();
93 handle.SetShaderEffect( newEffect );
95 Property::Index uModelProperty = newEffect.GetPropertyIndex( MOTION_STRETCH_MODELVIEW_LASTFRAME );
97 Constraint constraint = Constraint::New<Matrix>( uModelProperty,
98 Source( handle, Actor::WORLD_MATRIX ),
99 EqualToConstraint() );
101 // and set up constraint.
102 newEffect.ApplyConstraint(constraint);
106 MotionStretchEffect MotionStretchEffect::New()
108 // Dali vertexSource prefix for reference:
109 // precision highp float;
110 // attribute vec3 aPosition;
111 // attribute vec2 aTexCoord;
112 // uniform mat4 uMvpMatrix;
113 // uniform mat4 uModelView;
114 // uniform mat3 uNormalMatrix;
115 // uniform mat4 uProjection;
116 // uniform vec4 uColor;
117 // varying vec2 vTexCoord;
118 std::string vertexSource;
120 "uniform mat4 uModelLastFrame;\n"
121 "uniform float uTimeDelta;\n"
123 "uniform float uGeometryStretchFactor;\n"
124 "uniform float uSpeedScalingFactor;\n"
127 "varying vec2 vModelSpaceCenterToPos;\n"
128 "varying vec2 vScreenSpaceVelocityVector;\n"
129 "varying float vSpeed;\n"
133 // get view space position of vertex this frame and last frame
134 " vec4 vertex = vec4(aPosition, 1.0);\n"
135 " vec4 viewSpaceVertex = uModelView * vertex;\n"
136 " vec4 viewSpaceVertexLastFrame = uViewMatrix * uModelLastFrame * vertex;\n"
138 // work out vertex's last movement in view space
139 " vec3 viewSpacePosDelta = viewSpaceVertex.xyz - viewSpaceVertexLastFrame.xyz;\n"
140 " float reciprocalTimeDelta = 1.0 / ((uTimeDelta > 0.0) ? uTimeDelta : 0.01);\n"
142 // get clip space position of vertex this frame and last frame
143 " vec4 clipSpaceVertex = uMvpMatrix * vertex;\n"
144 " vec4 clipSpaceVertexLastFrame = uProjection * viewSpaceVertexLastFrame;\n"
146 // decide how much this vertex is 'trailing', i.e. at the back of the object relative to its direction of motion. We do this
147 // by assuming the objects model space origin is at its center and taking the dot product of the vector from center to vertex with the motion direction
149 " float posDeltaLength = length(viewSpacePosDelta);\n"
150 " if(posDeltaLength > 0.001)\n" // avoid div by 0 if object has barely moved
152 " vec4 viewSpaceCenterToPos = uModelView * vec4(aPosition, 0.0);\n"
153 " float centerToVertexDist = length(viewSpaceCenterToPos);\n"
154 " if(centerToVertexDist > 0.001)\n" // avoid div by 0 if object has vertex at model space origin
156 " vec3 viewSpacePosDeltaNormalised = viewSpacePosDelta / posDeltaLength;\n"
157 " vec3 viewSpaceCenterToPosNormalised = viewSpaceCenterToPos.xyz / centerToVertexDist;\n"
158 " t = (dot(viewSpacePosDeltaNormalised, viewSpaceCenterToPosNormalised) * 0.5 ) + 0.5;\n" // scale and bias from [-1..1] to [0..1]
161 // output vertex position lerped with its last position, based on how much it is trailing,
162 // this stretches the geom back along where it has just been, giving a warping effect
163 // We raise t to a power in order that non-trailing vertices are effected much more than trailing ones
164 // Note: we must take account of time delta to convert position delta into a velocity, so changes are smooth (take into account frame time correctly)
165 " gl_Position = mix(clipSpaceVertexLastFrame, clipSpaceVertex, t * t * t * uGeometryStretchFactor * reciprocalTimeDelta);\n"
167 // work out vertex's last movement in normalised device coordinates [-1..1] space, i.e. perspective divide
168 " vec2 ndcVertex = clipSpaceVertex.xy / clipSpaceVertex.w;\n"
169 " vec2 ndcVertexLastFrame = clipSpaceVertexLastFrame.xy / clipSpaceVertexLastFrame.w;\n"
170 // scale and bias so that a value of 1.0 corresponds to screen size (NDC is [-1..1] = 2)
171 " vScreenSpaceVelocityVector = ((ndcVertex - ndcVertexLastFrame) * 0.5 * reciprocalTimeDelta);\n"
172 " vScreenSpaceVelocityVector.y = -vScreenSpaceVelocityVector.y;\n" // TODO negated due to y being inverted in our coordinate system?
173 // calculate a scaling factor proportional to velocity, which we can use to tweak how things look
174 " vSpeed = length(vScreenSpaceVelocityVector) * uSpeedScalingFactor;\n"
175 " vSpeed = clamp(vSpeed, 0.0, 1.0);\n"
177 // provide fragment shader with vector from center of object to pixel (assumes the objects model space origin is at its center and verts have same z)
178 " vModelSpaceCenterToPos = aPosition.xy;\n"
180 " vTexCoord = aTexCoord;\n"
184 // Dali fragmentSource prefix for reference:
185 // precision highp float;
186 // uniform sampler2D sTexture;
187 // uniform sampler2D sEffect;
188 // uniform vec4 uColor;
189 // varying vec2 vTexCoord;
190 std::string fragmentSource;
192 "precision mediump float;\n"
194 "uniform vec2 uObjectFadeStart;\n"
195 "uniform vec2 uObjectFadeEnd;\n"
196 "uniform float uAlphaScale;\n"
199 "varying vec2 vModelSpaceCenterToPos;\n"
200 "varying vec2 vScreenSpaceVelocityVector;\n"
201 "varying float vSpeed;\n"
205 // calculate an alpha value that will fade the object towards its extremities, we need this to avoid an unsightly hard edge between color values of
206 // the stretched object and the background. Use smoothstep also to hide any hard edges (discontinuities) in rate of change of this alpha gradient
207 " vec2 centerToPixel = abs( vModelSpaceCenterToPos );\n"
208 " vec2 fadeToEdges = smoothstep(0.0, 1.0, 1.0 - ((centerToPixel - uObjectFadeStart) / (uObjectFadeEnd - uObjectFadeStart)));\n"
209 " float fadeToEdgesScale = fadeToEdges.x * fadeToEdges.y * uAlphaScale;\n" // apply global scaler
210 " fadeToEdgesScale = mix(1.0, fadeToEdgesScale, vSpeed);\n" // fade proportional to speed, so opaque when at rest
212 // standard actor texel
213 " vec4 colActor = texture2D(sTexture, vTexCoord);\n"
214 " gl_FragColor = colActor;\n"
215 " gl_FragColor.a *= fadeToEdgesScale;\n" // fade actor to its edges based on speed of motion
216 " gl_FragColor *= uColor;\n"
219 // NOTE: we must turn on alpha blending for the actor (HINT_BLENDING)
220 ShaderEffect shader = ShaderEffect::New( vertexSource,
222 GeometryType( GEOMETRY_TYPE_IMAGE ),
223 ShaderEffect::GeometryHints( ShaderEffect::HINT_BLENDING | ShaderEffect::HINT_GRID ) );
227 MotionStretchEffect handle( shader );
230 //////////////////////////////////////
231 // Register uniform properties
235 // factors that scale the look, defaults
236 handle.SetUniform( MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME, MOTION_STRETCH_GEOM_STRETCH_SCALING_FACTOR );
237 handle.SetUniform( MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME, MOTION_STRETCH_SPEED_SCALING_FACTOR );
238 handle.SetUniform( MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME, MOTION_STRETCH_OBJECT_FADE_START );
239 handle.SetUniform( MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME, MOTION_STRETCH_OBJECT_FADE_END );
240 handle.SetUniform( MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME, MOTION_STRETCH_ALPHA_SCALE );
241 handle.SetUniform( MOTION_STRETCH_MODELVIEW_LASTFRAME, Matrix::IDENTITY );
246 void MotionStretchEffect::SetGeometryStretchFactor( float scalingFactor )
248 SetUniform( MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME, scalingFactor );
251 void MotionStretchEffect::SetSpeedScalingFactor( float scalingFactor )
253 SetUniform( MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME, scalingFactor );
256 void MotionStretchEffect::SetObjectFadeStart( Vector2 displacement )
258 SetUniform( MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME, displacement );
261 void MotionStretchEffect::SetObjectFadeEnd( Vector2 displacement )
263 SetUniform( MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME, displacement );
266 void MotionStretchEffect::SetAlphaScale( float alphaScale )
268 SetUniform( MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME, alphaScale );
271 const std::string& MotionStretchEffect::GetGeometryStretchFactorPropertyName() const
273 return MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME;
276 const std::string& MotionStretchEffect::GetSpeedScalingFactorPropertyName() const
278 return MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME;
281 const std::string& MotionStretchEffect::GetObjectFadeStartPropertyName() const
283 return MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME;
286 const std::string& MotionStretchEffect::GetObjectFadeEndPropertyName() const
288 return MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME;
291 const std::string& MotionStretchEffect::GetAlphaScalePropertyName() const
293 return MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME;