Motion blur in C++ for animation tools

25 Oct 2023

Motion blur is a visual effect that simulates the blurring of moving objects in a scene, adding a sense of motion and speed. This effect is commonly used in animation tools to enhance the realism of animated sequences. In this blog post, we will explore how to implement motion blur in C++ for animation tools.

Introduction to Motion Blur
Implementing Motion Blur in C++
Conclusion

Introduction to Motion Blur

Motion blur is achieved by blending multiple frames of an object’s motion together, creating a blur effect along the trajectory. This effect depends on the speed of the object and the exposure time of the frame. By integrating the positions of the object over a given time range and blending them together, we can create the illusion of motion blur.

Implementing Motion Blur in C++

To implement motion blur in C++, we need to track the position of an animated object over a time range, and then blend the positions together to create the blur effect. Here is a simplified example of how we can achieve this:

#include <iostream>
#include <vector>

struct Point {
    float x;
    float y;
};

void applyMotionBlur(std::vector<Point>& positions, int blurFrames) {
    std::vector<Point> blurredPositions;

    for (int i = 0; i < positions.size(); i++) {
        Point blurredPosition = { 0.0f, 0.0f };
        int count = 0;

        for (int j = i - blurFrames; j <= i + blurFrames; j++) {
            if (j >= 0 && j < positions.size()) {
                blurredPosition.x += positions[j].x;
                blurredPosition.y += positions[j].y;
                count++;
            }
        }

        blurredPosition.x /= count;
        blurredPosition.y /= count;

        blurredPositions.push_back(blurredPosition);
    }

    // Replace the original positions with the blurred positions
    positions = blurredPositions;
}

int main() {
    std::vector<Point> positions = { { 0.0f, 0.0f }, { 1.0f, 1.0f }, { 2.0f, 2.0f }, { 3.0f, 3.0f }, { 4.0f, 4.0f } };

    // Apply motion blur with a blur range of 2 frames
    applyMotionBlur(positions, 2);

    // Print the blurred positions
    for (const auto& position : positions) {
        std::cout << "Blurred position: (" << position.x << ", " << position.y << ")" << std::endl;
    }

    return 0;
}

In this example, we have a Point struct representing the position of an animated object at a given time. The applyMotionBlur function takes in a vector of positions and the number of frames to consider for the blur effect. It calculates the blurred position for each frame by averaging the positions within the blur range. Finally, it replaces the original positions with the blurred positions.

The main function demonstrates how to use the applyMotionBlur function with a sample set of positions. It applies motion blur with a blur range of 2 frames and prints the resulting blurred positions.

Conclusion

Motion blur is an essential visual effect in animation tools that adds realism and enhances the sense of motion. By implementing motion blur in C++, we can create more dynamic and engaging animations. In this blog post, we explored a simple implementation of motion blur using C++ and discussed the basic concepts behind this visual effect.

Implementing motion blur in animation tools requires more advanced techniques, such as handling different types of motion, scaling blur based on object speed, and dealing with motion blur artifacts. However, this introductory example should give you a starting point for implementing motion blur in your own animation tools.

Table of Contents

Introduction to Motion Blur

Implementing Motion Blur in C++

Conclusion