2 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 #include <dali-toolkit/public-api/shader-effects/motion-stretch-effect.h>
22 #include <dali/public-api/animation/active-constraint.h>
23 #include <dali/public-api/animation/constraint.h>
24 #include <dali/public-api/animation/constraints.h>
25 #include <dali/public-api/actors/image-actor.h>
36 struct MatrixFromPropertiesConstraint
38 MatrixFromPropertiesConstraint()
42 Matrix operator()( const Matrix& current,
43 const PropertyInput& propertyPosition,
44 const PropertyInput& propertyOrientation,
45 const PropertyInput& propertyScale )
48 mat4.SetTransformComponents( propertyScale.GetVector3(),
49 propertyOrientation.GetQuaternion(),
50 propertyPosition.GetVector3() );
56 const std::string MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME( "uGeometryStretchFactor" );
57 const std::string MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME( "uSpeedScalingFactor" );
58 const std::string MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME( "uObjectFadeStart" );
59 const std::string MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME( "uObjectFadeEnd" );
60 const std::string MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME( "uAlphaScale" );
61 const std::string MOTION_STRETCH_MODELVIEW_LASTFRAME( "uModelLastFrame" ); ///< Matrix
63 ////////////////////////////////////////////////////
65 // Motion stretch shader / actor tweaking parameters
68 // half width and half height respectively of actor, corresponding to values in vertex attribute stream
69 // Note that these values work for normal image actor (verts +/- 0.5) but a grid or a nine square seemsi
70 // to have verts in pixel space (e.g. 256,256). Need to fix this somehow,
71 // either in Dali or by passing uniforms which we can use to 'normalise' the verts in the vertex shader
72 const Vector2 MOTION_STRETCH_ACTOR_VERTEX( 0.5f, 0.5f );
74 const float MOTION_STRETCH_GEOM_STRETCH_SCALING_FACTOR = 0.5f; // scaling factor for how much to stretch actor geom as it moves
75 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
77 const Vector2 MOTION_STRETCH_OBJECT_FADE_END( MOTION_STRETCH_ACTOR_VERTEX ); // displacement from center at which actor fully fades to zero alpha
78 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
80 const float MOTION_STRETCH_ALPHA_SCALE = 0.75f; // global scaler applied to actor alpha as it is stretched + moving
85 MotionStretchEffect::MotionStretchEffect()
89 // Call the Parent copy constructor to add reference to the implementation for this object
90 MotionStretchEffect::MotionStretchEffect( ShaderEffect handle )
91 :ShaderEffect( handle )
95 MotionStretchEffect::~MotionStretchEffect()
99 MotionStretchEffect MotionStretchEffect::Apply( RenderableActor renderable )
101 MotionStretchEffect newEffect = New();
103 ImageActor imageActor = ImageActor::DownCast(renderable);
106 imageActor.SetShaderEffect( newEffect );
109 Dali::Property::Index uModelProperty = newEffect.GetPropertyIndex( MOTION_STRETCH_MODELVIEW_LASTFRAME );
111 Constraint constraint = Constraint::New<Matrix>( uModelProperty,
112 Source( renderable, Actor::Property::WorldMatrix ),
113 EqualToConstraint() );
115 // and set up constraint.
116 newEffect.ApplyConstraint(constraint);
120 MotionStretchEffect MotionStretchEffect::New()
122 // Dali vertexSource prefix for reference:
123 // precision highp float;
124 // attribute vec3 aPosition;
125 // attribute vec2 aTexCoord;
126 // uniform mat4 uMvpMatrix;
127 // uniform mat4 uModelView;
128 // uniform mat3 uNormalMatrix;
129 // uniform mat4 uProjection;
130 // uniform vec4 uColor;
131 // varying vec2 vTexCoord;
132 std::string vertexSource;
134 "precision mediump float;\n"
135 "uniform mat4 uModelLastFrame;\n"
136 "uniform float uTimeDelta;\n"
138 "uniform float uGeometryStretchFactor;\n"
139 "uniform float uSpeedScalingFactor;\n"
142 "varying vec2 vModelSpaceCenterToPos;\n"
143 "varying vec2 vScreenSpaceVelocityVector;\n"
144 "varying float vSpeed;\n"
148 // get view space position of vertex this frame and last frame
149 " vec4 vertex = vec4(aPosition, 1.0);\n"
150 " vec4 viewSpaceVertex = uModelView * vertex;\n"
151 " vec4 viewSpaceVertexLastFrame = uViewMatrix * uModelLastFrame * vertex;\n"
153 // work out vertex's last movement in view space
154 " vec3 viewSpacePosDelta = viewSpaceVertex.xyz - viewSpaceVertexLastFrame.xyz;\n"
155 " float reciprocalTimeDelta = 1.0 / ((uTimeDelta > 0.0) ? uTimeDelta : 0.01);\n"
157 // get clip space position of vertex this frame and last frame
158 " vec4 clipSpaceVertex = uMvpMatrix * vertex;\n"
159 " vec4 clipSpaceVertexLastFrame = uProjection * viewSpaceVertexLastFrame;\n"
161 // decide how much this vertex is 'trailing', i.e. at the back of the object relative to its direction of motion. We do this
162 // 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
164 " float posDeltaLength = length(viewSpacePosDelta);\n"
165 " if(posDeltaLength > 0.001)\n" // avoid div by 0 if object has barely moved
167 " vec4 viewSpaceCenterToPos = uModelView * vec4(aPosition, 0.0);\n"
168 " float centerToVertexDist = length(viewSpaceCenterToPos);\n"
169 " if(centerToVertexDist > 0.001)\n" // avoid div by 0 if object has vertex at model space origin
171 " vec3 viewSpacePosDeltaNormalised = viewSpacePosDelta / posDeltaLength;\n"
172 " vec3 viewSpaceCenterToPosNormalised = viewSpaceCenterToPos.xyz / centerToVertexDist;\n"
173 " t = (dot(viewSpacePosDeltaNormalised, viewSpaceCenterToPosNormalised) * 0.5 ) + 0.5;\n" // scale and bias from [-1..1] to [0..1]
176 // output vertex position lerped with its last position, based on how much it is trailing,
177 // this stretches the geom back along where it has just been, giving a warping effect
178 // We raise t to a power in order that non-trailing vertices are effected much more than trailing ones
179 // 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)
180 " gl_Position = mix(clipSpaceVertexLastFrame, clipSpaceVertex, t * t * t * uGeometryStretchFactor * reciprocalTimeDelta);\n"
182 // work out vertex's last movement in normalised device coordinates [-1..1] space, i.e. perspective divide
183 " vec2 ndcVertex = clipSpaceVertex.xy / clipSpaceVertex.w;\n"
184 " vec2 ndcVertexLastFrame = clipSpaceVertexLastFrame.xy / clipSpaceVertexLastFrame.w;\n"
185 // scale and bias so that a value of 1.0 corresponds to screen size (NDC is [-1..1] = 2)
186 " vScreenSpaceVelocityVector = ((ndcVertex - ndcVertexLastFrame) * 0.5 * reciprocalTimeDelta);\n"
187 " vScreenSpaceVelocityVector.y = -vScreenSpaceVelocityVector.y;\n" // TODO negated due to y being inverted in our coordinate system?
188 // calculate a scaling factor proportional to velocity, which we can use to tweak how things look
189 " vSpeed = length(vScreenSpaceVelocityVector) * uSpeedScalingFactor;\n"
190 " vSpeed = clamp(vSpeed, 0.0, 1.0);\n"
192 // 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)
193 " vModelSpaceCenterToPos = aPosition.xy;\n"
195 " vTexCoord = aTexCoord;\n"
199 // Dali fragmentSource prefix for reference:
200 // precision highp float;
201 // uniform sampler2D sTexture;
202 // uniform sampler2D sEffect;
203 // uniform vec4 uColor;
204 // varying vec2 vTexCoord;
205 std::string fragmentSource;
207 "precision mediump float;\n"
209 "uniform vec2 uObjectFadeStart;\n"
210 "uniform vec2 uObjectFadeEnd;\n"
211 "uniform float uAlphaScale;\n"
214 "varying vec2 vModelSpaceCenterToPos;\n"
215 "varying vec2 vScreenSpaceVelocityVector;\n"
216 "varying float vSpeed;\n"
220 // 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
221 // the stretched object and the background. Use smoothstep also to hide any hard edges (discontinuities) in rate of change of this alpha gradient
222 " vec2 centerToPixel = abs( vModelSpaceCenterToPos );\n"
223 " vec2 fadeToEdges = smoothstep(0.0, 1.0, 1.0 - ((centerToPixel - uObjectFadeStart) / (uObjectFadeEnd - uObjectFadeStart)));\n"
224 " float fadeToEdgesScale = fadeToEdges.x * fadeToEdges.y * uAlphaScale;\n" // apply global scaler
225 " fadeToEdgesScale = mix(1.0, fadeToEdgesScale, vSpeed);\n" // fade proportional to speed, so opaque when at rest
227 // standard actor texel
228 " vec4 colActor = texture2D(sTexture, vTexCoord);\n"
229 " gl_FragColor = colActor;\n"
230 " gl_FragColor.a *= fadeToEdgesScale;\n" // fade actor to its edges based on speed of motion
231 " gl_FragColor *= uColor;\n"
234 // NOTE: we must turn on alpha blending for the actor (HINT_BLENDING)
235 ShaderEffect shader = ShaderEffect::New(
236 vertexSource, fragmentSource, GeometryType( GEOMETRY_TYPE_IMAGE ),
237 ShaderEffect::GeometryHints( ShaderEffect::HINT_BLENDING | ShaderEffect::HINT_GRID ) );
241 MotionStretchEffect handle( shader );
244 //////////////////////////////////////
245 // Register uniform properties
249 // factors that scale the look, defaults
250 handle.SetUniform( MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME, MOTION_STRETCH_GEOM_STRETCH_SCALING_FACTOR );
251 handle.SetUniform( MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME, MOTION_STRETCH_SPEED_SCALING_FACTOR );
252 handle.SetUniform( MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME, MOTION_STRETCH_OBJECT_FADE_START );
253 handle.SetUniform( MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME, MOTION_STRETCH_OBJECT_FADE_END );
254 handle.SetUniform( MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME, MOTION_STRETCH_ALPHA_SCALE );
255 handle.SetUniform( MOTION_STRETCH_MODELVIEW_LASTFRAME, Matrix::IDENTITY );
260 void MotionStretchEffect::SetGeometryStretchFactor( float scalingFactor )
262 SetUniform( MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME, scalingFactor );
265 void MotionStretchEffect::SetSpeedScalingFactor( float scalingFactor )
267 SetUniform( MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME, scalingFactor );
270 void MotionStretchEffect::SetObjectFadeStart( Vector2 displacement )
272 SetUniform( MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME, displacement );
275 void MotionStretchEffect::SetObjectFadeEnd( Vector2 displacement )
277 SetUniform( MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME, displacement );
280 void MotionStretchEffect::SetAlphaScale( float alphaScale )
282 SetUniform( MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME, alphaScale );
285 const std::string& MotionStretchEffect::GetGeometryStretchFactorPropertyName() const
287 return MOTION_STRETCH_GEOMETRY_STRETCH_SCALING_FACTOR_PROPERTY_NAME;
290 const std::string& MotionStretchEffect::GetSpeedScalingFactorPropertyName() const
292 return MOTION_STRETCH_SPEED_SCALING_FACTOR_PROPERTY_NAME;
295 const std::string& MotionStretchEffect::GetObjectFadeStartPropertyName() const
297 return MOTION_STRETCH_OBJECT_FADE_START_PROPERTY_NAME;
300 const std::string& MotionStretchEffect::GetObjectFadeEndPropertyName() const
302 return MOTION_STRETCH_OBJECT_FADE_END_PROPERTY_NAME;
305 const std::string& MotionStretchEffect::GetAlphaScalePropertyName() const
307 return MOTION_STRETCH_ALPHA_SCALE_PROPERTY_NAME;