*/
// EXTERNAL INCLUDES
-#include <dali/public-api/actors/renderable-actor.h>
+#include <dali/public-api/actors/image-actor.h>
#include <dali/public-api/shader-effects/shader-effect.h>
namespace Dali
{
/**
+ * @brief Creates a new MotionStretchEffect
*
- * Class for motion stretch shader that works on a per object basis. Objects will stretch in the direction of motion when they move, or if the camera moves. Can be applied
+ * Motion stretch shader works on a per object basis. Objects will stretch in the direction of motion when they move, or if the camera moves. Can be applied
* to ImageActor or TextActor only.
*
* Usage example:-
*
* // Create shader used for doing motion stretch\n
- * MotionStretchEffect MotionStretchEffect = MotionStretchEffect::New();
+ * ShaderEffect MotionStretchEffect = CreateMotionStretchEffect();
*
* // set actor shader to the stretch one\n
- * Actor Actor = Actor::New( ... );\n
- * Actor.SetShaderEffect( MotionStretchEffect );
+ * Actor actor = Actor::New( ... );\n
+ * actor.SetShaderEffect( MotionStretchEffect );
*
+ * // Constrain "uModelLastFrame" to be the same as the actor's world matrix\n
+ * Dali::Property::Index uModelProperty = MotionBlurEffect.GetPropertyIndex( "uModelLastFrame" );
+ * Constraint constraint = Constraint::New<Matrix>( MotionBlurEffect, uModelProperty, EqualToConstraint() );\n
+ * constraint.AddSource( Source( actor , Actor::Property::WORLD_MATRIX ) );\n
+ * constraint.Apply();\n
+ *
+ * Animatable/Constrainable uniforms:
+ * "uGeometryStretchFactor" - This scales the amount the geometry stretches along the motion velocity vector.
+ * A smaller value means the geometry stretches less, larger it stretches more. Default 0.5.
+ * "uSpeedScalingFactor" - This value is used to control how much to fade the actor near the edges, based on the
+ * speed the actor is moving. When the actor is at rest this is not applied. Default 0.5.
+ * "uObjectFadeStart" - The displacement from the centre of the actor that the actor will start to fade towards
+ * its edges. This is used to prevent an unsightly hard edge between the stretched actor and
+ * the scene. Depends on the values of the vertices in the vertex stream. When the actor is at
+ * rest this is not applied. Default Vector2(0.25, 0.25), which is half way towards the edge for
+ * an ImageRenderer::QUAD.
+ * "uObjectFadeEnd" - The displacement from the centre of the actor that the actor will finish fading towards its edges.
+ * This is used to prevent an unsightly hard edge between the stretched actor and the scene. Depends
+ * on the values of the vertices in the vertex stream. When the actor is at rest this is not applied.
+ * Default 0.5, which is all the way towards the edge for an ImageRenderer::QUAD.
+ * "uAlphaScale" - Global scaler applied to the alpha of the actor. Used to make the stretched actor a bit more subtle
+ * and reveal a bit of the background behind it as it moves. When the actor is at rest this is not
+ * applied. Default 0.75.
+ * "uModelLastFrame" - The model to world space transformation matrix of the actor in the previous frame.
+ *
+ * @return A handle to a newly allocated ShaderEffect
*/
-class DALI_IMPORT_API MotionStretchEffect : public ShaderEffect
+inline ShaderEffect CreateMotionStretchEffect()
{
-
-public:
-
- /**
- * Create an uninitialized MotionStretchEffect; this can be initialized with MotionStretchEffect::New()
- * Calling member functions with an uninitialized Dali::Object is not allowed.
- */
- MotionStretchEffect();
-
- /**
- * @brief Destructor
- *
- * This is non-virtual since derived Handle types must not contain data or virtual methods.
- */
- ~MotionStretchEffect();
-
- /**
- * Create an initialized MotionStretchEffect
- * @return A handle to a newly allocated Dali resource.
- */
- static MotionStretchEffect New();
-
- /**
- * Create a MotionStretchEffect and attach it to the specified actor
- * @param renderable actor to apply the effect to
- * @return A handle to a newly allocated Dali resource.
- */
- static MotionStretchEffect Apply( RenderableActor renderable );
-
- /**
- * Set geometry stretch factor property. This scales the amount the geometry
- * stretches along the motion velocity vector. A smaller value means the geometry
- * stretches less, larger it stretches more. Default 0.5.
- * @param scalingFactor The scaling factor that extrudes the geometry forwards along the motion velocity vector.
- */
- void SetGeometryStretchFactor( float scalingFactor );
-
- /**
- * Set speed scaling factor property. This value is used to control how much
- * to fade the actor near the edges, based on the speed the actor is moving.
- * When the actor is at rest this is not applied. Default 0.5.
- * @param scalingFactor The scaling factor that controls the edge fade of the actor.
- */
- void SetSpeedScalingFactor( float scalingFactor );
-
- /**
- * Set the displacement from the centre of the actor that the actor will start to
- * fade towards its edges. This is used to prevent an unsightly hard edge
- * between the stretched actor and the scene. Depends on the values of the
- * vertices in the vertex stream. When the actor is at rest this is not applied.
- * Default Vector2(0.25, 0.25), which is half way towards the edge for an ImageRenderer::QUAD.
- * @param displacement The displacement from the centre of the actor that the actor will start to edge fade.
- */
- void SetObjectFadeStart( Vector2 displacement );
-
- /**
- * Set the displacement from the centre of the actor that the actor will
- * finish fading towards its edges. This is used to prevent an unsightly hard
- * edge between the stretched actor and the scene. Depends on the values of
- * the vertices in the vertex stream. When the actor is at rest this is not applied.
- * Default 0.5, which is all the way towards the edge for an ImageRenderer::QUAD.
- * @param displacement The displacement from the centre of the actor that the actor will finish edge fading.
- */
- void SetObjectFadeEnd( Vector2 displacement );
-
- /**
- * Set a global scaler applied to the alpha of the actor. Used to make the
- * stretched actor a bit more subtle and reveal a bit of the background behind
- * it as it moves. When the actor is at rest this is not applied. Default 0.75.
- * @param alphaScale The scaling factor which multiplies the alpha of each pixel of the actor.
- */
- void SetAlphaScale( float alphaScale );
-
-
- /**
- * Get the name for the texcoord scale property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetTexcoordScalePropertyName() const;
-
- /**
- * Get the name for the geometry stretching property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetGeometryStretchFactorPropertyName() const;
-
- /**
- * Get the name for the speed scaling property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetSpeedScalingFactorPropertyName() const;
-
- /**
- * Get the name for the fade start X property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetObjectFadeStartPropertyName() const;
-
- /**
- * Get the name for the fade end X property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetObjectFadeEndPropertyName() const;
-
- /**
- * Get the name for the alpha scale property. Useful for animation.
- * @return A std::string containing the property name
- */
- const std::string& GetAlphaScalePropertyName() const;
-
-private:
- // Not intended for application developers
- DALI_INTERNAL MotionStretchEffect( ShaderEffect handle );
-};
+ // Dali vertexSource prefix for reference:
+ // precision highp float;
+ // attribute vec3 aPosition;
+ // attribute vec2 aTexCoord;
+ // uniform mat4 uMvpMatrix;
+ // uniform mat4 uModelView;
+ // uniform mat3 uNormalMatrix;
+ // uniform mat4 uProjection;
+ // uniform vec4 uColor;
+ // varying vec2 vTexCoord;
+ std::string vertexSource;
+ vertexSource =
+ "precision mediump float;\n"
+ "uniform mat4 uModelLastFrame;\n"
+ "uniform float uTimeDelta;\n"
+
+ "uniform float uGeometryStretchFactor;\n"
+ "uniform float uSpeedScalingFactor;\n"
+
+ // outputs
+ "varying vec2 vModelSpaceCenterToPos;\n"
+ "varying vec2 vScreenSpaceVelocityVector;\n"
+ "varying float vSpeed;\n"
+
+ "void main()\n"
+ "{\n"
+ // get view space position of vertex this frame and last frame
+ " vec4 vertex = vec4(aPosition, 1.0);\n"
+ " vec4 viewSpaceVertex = uModelView * vertex;\n"
+ " vec4 viewSpaceVertexLastFrame = uViewMatrix * uModelLastFrame * vertex;\n"
+
+ // work out vertex's last movement in view space
+ " vec3 viewSpacePosDelta = viewSpaceVertex.xyz - viewSpaceVertexLastFrame.xyz;\n"
+ " float reciprocalTimeDelta = 1.0 / ((uTimeDelta > 0.0) ? uTimeDelta : 0.01);\n"
+
+ // get clip space position of vertex this frame and last frame
+ " vec4 clipSpaceVertex = uMvpMatrix * vertex;\n"
+ " vec4 clipSpaceVertexLastFrame = uProjection * viewSpaceVertexLastFrame;\n"
+
+ // decide how much this vertex is 'trailing', i.e. at the back of the object relative to its direction of motion. We do this
+ // 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
+ " float t = 0.0;\n"
+ " float posDeltaLength = length(viewSpacePosDelta);\n"
+ " if(posDeltaLength > 0.001)\n" // avoid div by 0 if object has barely moved
+ " {\n"
+ " vec4 viewSpaceCenterToPos = uModelView * vec4(aPosition, 0.0);\n"
+ " float centerToVertexDist = length(viewSpaceCenterToPos);\n"
+ " if(centerToVertexDist > 0.001)\n" // avoid div by 0 if object has vertex at model space origin
+ " {\n"
+ " vec3 viewSpacePosDeltaNormalised = viewSpacePosDelta / posDeltaLength;\n"
+ " vec3 viewSpaceCenterToPosNormalised = viewSpaceCenterToPos.xyz / centerToVertexDist;\n"
+ " t = (dot(viewSpacePosDeltaNormalised, viewSpaceCenterToPosNormalised) * 0.5 ) + 0.5;\n" // scale and bias from [-1..1] to [0..1]
+ " }\n"
+ " }\n"
+ // output vertex position lerped with its last position, based on how much it is trailing,
+ // this stretches the geom back along where it has just been, giving a warping effect
+ // We raise t to a power in order that non-trailing vertices are effected much more than trailing ones
+ // 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)
+ " gl_Position = mix(clipSpaceVertexLastFrame, clipSpaceVertex, t * t * t * uGeometryStretchFactor * reciprocalTimeDelta);\n"
+
+ // work out vertex's last movement in normalised device coordinates [-1..1] space, i.e. perspective divide
+ " vec2 ndcVertex = clipSpaceVertex.xy / clipSpaceVertex.w;\n"
+ " vec2 ndcVertexLastFrame = clipSpaceVertexLastFrame.xy / clipSpaceVertexLastFrame.w;\n"
+ // scale and bias so that a value of 1.0 corresponds to screen size (NDC is [-1..1] = 2)
+ " vScreenSpaceVelocityVector = ((ndcVertex - ndcVertexLastFrame) * 0.5 * reciprocalTimeDelta);\n"
+ " vScreenSpaceVelocityVector.y = -vScreenSpaceVelocityVector.y;\n" // TODO negated due to y being inverted in our coordinate system?
+ // calculate a scaling factor proportional to velocity, which we can use to tweak how things look
+ " vSpeed = length(vScreenSpaceVelocityVector) * uSpeedScalingFactor;\n"
+ " vSpeed = clamp(vSpeed, 0.0, 1.0);\n"
+
+ // 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)
+ " vModelSpaceCenterToPos = aPosition.xy;\n"
+
+ " vTexCoord = aTexCoord;\n"
+ "}\n";
+
+
+ // Dali fragmentSource prefix for reference:
+ // precision highp float;
+ // uniform sampler2D sTexture;
+ // uniform sampler2D sEffect;
+ // uniform vec4 uColor;
+ // varying vec2 vTexCoord;
+ std::string fragmentSource;
+ fragmentSource =
+ "precision mediump float;\n"
+
+ "uniform vec2 uObjectFadeStart;\n"
+ "uniform vec2 uObjectFadeEnd;\n"
+ "uniform float uAlphaScale;\n"
+
+ // inputs
+ "varying vec2 vModelSpaceCenterToPos;\n"
+ "varying vec2 vScreenSpaceVelocityVector;\n"
+ "varying float vSpeed;\n"
+
+ "void main()\n"
+ "{\n"
+ // 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
+ // the stretched object and the background. Use smoothstep also to hide any hard edges (discontinuities) in rate of change of this alpha gradient
+ " vec2 centerToPixel = abs( vModelSpaceCenterToPos );\n"
+ " vec2 fadeToEdges = smoothstep(0.0, 1.0, 1.0 - ((centerToPixel - uObjectFadeStart) / (uObjectFadeEnd - uObjectFadeStart)));\n"
+ " float fadeToEdgesScale = fadeToEdges.x * fadeToEdges.y * uAlphaScale;\n" // apply global scaler
+ " fadeToEdgesScale = mix(1.0, fadeToEdgesScale, vSpeed);\n" // fade proportional to speed, so opaque when at rest
+
+ // standard actor texel
+ " vec4 colActor = texture2D(sTexture, vTexCoord);\n"
+ " gl_FragColor = colActor;\n"
+ " gl_FragColor.a *= fadeToEdgesScale;\n" // fade actor to its edges based on speed of motion
+ " gl_FragColor *= uColor;\n"
+ "}";
+
+ // NOTE: we must turn on alpha blending for the actor (HINT_BLENDING)
+ ShaderEffect shaderEffect = ShaderEffect::New(
+ vertexSource, fragmentSource, GeometryType( GEOMETRY_TYPE_IMAGE ),
+ ShaderEffect::GeometryHints( ShaderEffect::HINT_BLENDING | ShaderEffect::HINT_GRID ) );
+
+
+ //////////////////////////////////////
+ // Register uniform properties
+ //
+ //
+ shaderEffect.SetUniform( "uGeometryStretchFactor", 0.5f );
+ shaderEffect.SetUniform( "uSpeedScalingFactor", 0.5f );
+ shaderEffect.SetUniform( "uObjectFadeStart", Vector2( 0.25f, 0.25f ) );
+ shaderEffect.SetUniform( "uObjectFadeEnd", Vector2( 0.5f, 0.5f ) );
+ shaderEffect.SetUniform( "uAlphaScale", 0.75f );
+ shaderEffect.SetUniform( "uModelLastFrame", Matrix::IDENTITY );
+
+ return shaderEffect;
+}
}
projects / platform / core / uifw / dali-toolkit.git / blobdiff