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[platform/core/uifw/dali-toolkit.git] / dali-toolkit / devel-api / shader-effects / motion-blur-effect.h

#ifndef DALI_TOOLKIT_SHADER_EFFECT_MOTION_BLUR_H
#define DALI_TOOLKIT_SHADER_EFFECT_MOTION_BLUR_H

/*
 * Copyright (c) 2020 Samsung Electronics Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

// EXTERNAL INCLUDES
#include <dali/public-api/actors/actor.h>
#include <dali/public-api/animation/constraint.h>
#include <dali/public-api/object/property-map.h>
#include <dali/public-api/rendering/shader.h>

// INTERNAL INCLUDES
#include <dali-toolkit/public-api/visuals/visual-properties.h>

namespace Dali
{
namespace Toolkit
{
/**
 * @brief Set the properties for the motion blur
 *
 * @param[in] actor The actor that registers the uniform properties
 * @param[in] numBlurSamples Number of samples used by the shader
 */
inline void SetMotionBlurProperties(Actor& actor, unsigned int numBlurSamples = 8)
{
  actor.RegisterProperty("uBlurTexCoordScale", 0.125f);
  actor.RegisterProperty("uGeometryStretchFactor", 0.05f);
  actor.RegisterProperty("uSpeedScalingFactor", 0.5f);
  actor.RegisterProperty("uObjectFadeStart", Vector2(0.25f, 0.25f));
  actor.RegisterProperty("uObjectFadeEnd", Vector2(0.5f, 0.5f));
  actor.RegisterProperty("uAlphaScale", 0.75f);
  actor.RegisterProperty("uNumSamples", static_cast<float>(numBlurSamples));
  actor.RegisterProperty("uRecipNumSamples", 1.0f / static_cast<float>(numBlurSamples));
  actor.RegisterProperty("uRecipNumSamplesMinusOne", 1.0f / static_cast<float>(numBlurSamples - 1.0f));
  Property::Index uModelProperty = actor.RegisterProperty("uModelLastFrame", Matrix::IDENTITY);

  Constraint constraint = Constraint::New<Matrix>(actor, uModelProperty, EqualToConstraint());
  constraint.AddSource(Source(actor, Actor::Property::WORLD_MATRIX));
  constraint.Apply();
}

/**
 * @brief Create a new MotionBlurEffect
 *
 * Motion blur shader works on a per object basis. Objects will
 * blur when they move, or if the camera moves.
 *
 * Animatable/Constrainable uniforms:
 *  "uBlurTexCoordScale"      - This scales the offset for texture samples along the motion velocity vector.
 *                              A smaller value means the samples will be spaced closer, larger value further
 *                              apart. User should use this to get the blur to look contiguous, i.e. the blur
 *                              texels should not be too widely spread, with gaps in between. Default 0.125.
 *  "uGeometryStretchFactor"  - This scales the amount the geometry stretches backwards along the motion velocity
 *                              vector. A smaller value means the geometry stretches less, larger it stretches more.
 *                              User should use this to get the blur to 'bleed' into areas outside the physical
 *                              bounds of the actor. We need this as the blur is only applied inside the bounds of
 *                              the actor, but you would expect motion blur trails where the actor was previously
 *                              but is there no longer. Default 0.05.
 *  "uSpeedScalingFactor"     - This takes the magnitude of the motion velocity vector and scales it to produce a
 *                              value which is used to fade the blur in / out with the speed that the actor is moving.
 *                              As the blur fades in, more of the blur is visible and less of the original actor, and
 *                              viceversa. This value is also 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 blurred 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 0.25, which is half way towards the edge for an ImageVisual::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 blurred 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 ImageVisual::QUAD.
 *  "uAlphaScale"             - Global scaler applied to the alpha of the actor. Used to make the blurred actor a bit more subtle
 *                              (helps to hide discontinuities due to limited number of texture samples) 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.
 *  "uNumSamples"             - The number of texture samples to be taken. Increasing the number of samples provides better quality
 *                              at the cost of performance.
 *  "uModelLastFrame"         - The model to world space transformation matrix of the actor in the previous frame.
 *
 * @return The newly created Property::Map with the motion blur effect
 */
inline Property::Map CreateMotionBlurEffect()
{
  std::string vertexSource;
  vertexSource =
    "precision mediump float;\n"

    "attribute vec2 aPosition;\n"

    "uniform mat4 uMvpMatrix;\n"
    "uniform mat4 uModelView;\n"
    "uniform mat4 uViewMatrix;\n"
    "uniform mat4 uProjection;\n"
    "uniform vec3 uSize;\n"

    "uniform mat4 uModelLastFrame;\n"
    "float timeDelta = 0.0167;\n"

    "uniform float uGeometryStretchFactor;\n"
    "uniform float uSpeedScalingFactor;\n"

    // outputs
    "varying vec2 vModelSpaceCenterToPos;\n"
    "varying vec2 vScreenSpaceVelocityVector;\n"
    "varying float vSpeed;\n"
    "varying vec2 vTexCoord;\n"

    "void main()\n"
    "{\n"
    // get view space position of vertex this frame and last frame
    " vec4 vertexPosition = vec4(aPosition, 0.0, 1.0);\n"
    " vertexPosition.xyz *= uSize;\n"

    " vec4 viewSpaceVertex = uModelView * vertexPosition;\n"
    " vec4 viewSpaceVertexLastFrame = (uViewMatrix * uModelLastFrame) * vertexPosition;\n"
    " float reciprocalTimeDelta = 1.0 / timeDelta;\n"

    // work out vertex's last movement in view space
    " vec3 viewSpacePosDelta = viewSpaceVertex.xyz - viewSpaceVertexLastFrame.xyz;\n"

    // get clip space position of vertex this frame and last frame
    " vec4 clipSpaceVertex = uMvpMatrix * vertexPosition;\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(vertexPosition.xy, 0.0, 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
    // 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 * 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 = viewSpaceVertex.xy;\n"

    " vec2 texCoord = aPosition + vec2(0.5);"
    " vTexCoord = texCoord;\n"
    "}\n";

  std::string fragmentSource;
  fragmentSource =
    "precision mediump float;\n"

    "uniform sampler2D sTexture;\n"
    "uniform vec4 uColor;\n"

    "uniform vec2 uObjectFadeStart;\n"
    "uniform vec2 uObjectFadeEnd;\n"
    "uniform float uAlphaScale;\n"
    "uniform float uBlurTexCoordScale;\n"
    "uniform float uNumSamples;\n"
    "uniform float uRecipNumSamples;\n"
    "uniform float uRecipNumSamplesMinusOne;\n"
    // inputs
    "varying vec2 vModelSpaceCenterToPos;\n"
    "varying vec2 vScreenSpaceVelocityVector;\n"
    "varying float vSpeed;\n"
    "varying vec2 vTexCoord;\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 blurred object and the unblurred 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

    // scale velocity vector by user requirements
    " vec2 velocity = vScreenSpaceVelocityVector * uBlurTexCoordScale;\n"

    // standard actor texel
    " vec4 colActor = texture2D(sTexture, vTexCoord);\n"

    // blurred actor - gather texture samples from the actor texture in the direction of motion
    " vec4 col = colActor * uRecipNumSamples;\n"
    " for(float i = 1.0; i < uNumSamples; i += 1.0)\n"
    " {\n"
    "   float t = i * uRecipNumSamplesMinusOne;\n"
    "   col += texture2D(sTexture, vTexCoord + (velocity * t)) * uRecipNumSamples;\n"
    " }\n"
    " gl_FragColor = mix(colActor, col, vSpeed);\n"                         // lerp blurred and non-blurred actor based on speed of motion
    " gl_FragColor.a = fadeToEdgesScale;//colActor.a * fadeToEdgesScale;\n" // fade blurred actor to its edges based on speed of motion
    " gl_FragColor *= uColor;\n"
    "}\n";

  Property::Map map;

  Property::Map customShader;
  customShader[Visual::Shader::Property::VERTEX_SHADER]   = vertexSource;
  customShader[Visual::Shader::Property::FRAGMENT_SHADER] = fragmentSource;

  customShader[Visual::Shader::Property::SUBDIVIDE_GRID_X] = 10;
  customShader[Visual::Shader::Property::SUBDIVIDE_GRID_Y] = 10;

  customShader[Visual::Shader::Property::HINTS] = Shader::Hint::OUTPUT_IS_TRANSPARENT;

  map[Toolkit::Visual::Property::SHADER] = customShader;
  return map;
}

} // namespace Toolkit

} // namespace Dali

#endif // DALI_TOOLKIT_SHADER_EFFECT_MOTION_BLUR_H