C++ graphics programming performance improvement tips

Optimize memory allocation: avoid dynamic memory allocation, use memory pools and cache data. Use multithreading: Distribute computing tasks to multiple threads to increase parallelism. Optimize the rendering process: batch render calls, culling invisible objects, using GPU shaders. Practical case: Use VAO and VBO to optimize triangle rendering code, avoid the overhead of each call to glBegin() and glEnd(), and improve loading efficiency.

C++ graphics programming performance improvement tips

Preface

In graphics programming, performance is crucial. Lagging animations or dropped frame rates can ruin the user experience. This article will share some practical tips to improve the performance of C++ graphics programming.

1. Optimize memory allocation

• Use the memory pool to allocate and release frequently used objects to avoid the overhead of multiple allocations and releases.
• Avoid dynamic memory allocation (e.g. new) as it is slower than using stack allocation.

2. Cache data

• Cache frequently read data to avoid repeated access to memory.
• Using the const keyword to declare objects that will not change allows the compiler to optimize access to them.

const std::vector<Vertex> vertices = ...;

3. Use multi-threading

• Allocate computing-intensive tasks to multiple threads to improve parallelism.
• Use the thread classes from the modern C++ standard (std::thread).

std::vector<std::thread> threads;
for (int i = 0; i < num_threads; i++) {
  threads.push_back(std::thread(&Worker, this, i));
}

4. Optimize the rendering process

• Batch rendering calls: Aggregate multiple rendering calls into one batch middle.
• Culling: Culling objects that are invisible or too far from the camera.
• Use GPU shaders: Move complex calculations to the GPU to increase processing speed.

5. Use tools and libraries

• Analysis tools:For example, Visual Studio’s Performance Analyzer can be used to identify Performance bottleneck.
• Graphics library: Such as DirectX, OpenGL or Vulkan, which provides a performance-optimized graphics API.

Practical Case

Let’s apply these techniques to optimize a simple triangle rendering program.

Original code:

void RenderTriangle() {
  for (int i = 0; i < num_triangles; i++) {
    glBegin(GL_TRIANGLES);
    glVertex3f(vertices[3 * i], vertices[3 * i + 1], vertices[3 * i + 2]);
    glVertex3f(vertices[3 * i + 3], vertices[3 * i + 4], vertices[3 * i + 5]);
    glVertex3f(vertices[3 * i + 6], vertices[3 * i + 7], vertices[3 * i + 8]);
    glEnd();
  }
}

Optimized code:

void RenderTriangle() {
  static const GLuint vao = ...;
  static const GLuint vbo = ...;

  glBindVertexArray(vao);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
  glEnableVertexAttribArray(0);
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), reinterpret_cast<void*>(0));
  glDrawArrays(GL_TRIANGLES, 0, num_triangles * 3);
}

By using Vertex Array Object (VAO) and Vertex Buffer Object (VBO), we can avoid the heavy overhead of each The overhead of calling glBegin() and glEnd(). Additionally, glBufferData() allows entire vertex data to be loaded to the GPU at once, improving rendering efficiency.

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