always liked the look of these sort of background so thought id have a go at making one and think it has came out pretty good
Initializes the particles setting the x and y to random and sets the velocity which will be used later to set the position
static bool initialized = false;
if (!initialized)
{
for (int i = 0; i < numParticles; ++i)
{
particlePositions[i] = ImVec2(
ImGui::GetWindowPos().x + ImGui::GetWindowSize().x * static_cast<float>(rand()) / RAND_MAX,
ImGui::GetWindowPos().y + ImGui::GetWindowSize().y * static_cast<float>(rand()) / RAND_MAX
);
particleVelocities[i] = ImVec2(
static_cast<float>((rand() % 11) - 5),
static_cast<float>((rand() % 11) - 5)
);
}
initialized = true;
}Draws the lines to the cursor and particles depending on the distance
ImVec2 cursorPos = ImGui::GetIO().MousePos;
for (int i = 0; i < numParticles; ++i)
{
//draw lines to particles
for (int j = i + 1; j < numParticles; ++j)
{
float distance = std::hypotf(particlePositions[j].x - particlePositions[i].x, particlePositions[j].y - particlePositions[i].y);
float opacity = 1.0f - (distance / 55.0f); // opacity cahnge
if (opacity > 0.0f)
{
ImU32 lineColor = ImGui::GetColorU32(ImVec4(1.0f, 1.0f, 1.0f, opacity));
drawList->AddLine(particlePositions[i], particlePositions[j], lineColor);
}
}
//draw lines to cursor
float distanceToCursor = std::hypotf(cursorPos.x - particlePositions[i].x, cursorPos.y - particlePositions[i].y);
float opacityToCursor = 1.0f - (distanceToCursor / 52.0f); // Adjust the divisor to control the opacity change
if (opacityToCursor > 0.0f)
{
ImU32 lineColorToCursor = ImGui::GetColorU32(ImVec4(1.0f, 1.0f, 1.0f, opacityToCursor));
drawList->AddLine(cursorPos, particlePositions[i], lineColorToCursor);
}
}Updates adn renders the particles setting the positions, keeping them in bound of the window and setting the colour
float deltaTime = ImGui::GetIO().DeltaTime;
for (int i = 0; i < numParticles; ++i)
{
particlePositions[i].x += particleVelocities[i].x * deltaTime;
particlePositions[i].y += particleVelocities[i].y * deltaTime;
// Stay in window
if (particlePositions[i].x < ImGui::GetWindowPos().x)
particlePositions[i].x = ImGui::GetWindowPos().x + ImGui::GetWindowSize().x;
else if (particlePositions[i].x > ImGui::GetWindowPos().x + ImGui::GetWindowSize().x)
particlePositions[i].x = ImGui::GetWindowPos().x;
if (particlePositions[i].y < ImGui::GetWindowPos().y)
particlePositions[i].y = ImGui::GetWindowPos().y + ImGui::GetWindowSize().y;
else if (particlePositions[i].y > ImGui::GetWindowPos().y + ImGui::GetWindowSize().y)
particlePositions[i].y = ImGui::GetWindowPos().y;
ImU32 particleColour = ImGui::ColorConvertFloat4ToU32(settings::particleColour);
//render particles behind components
drawList->AddCircleFilled(particlePositions[i], 1.5f, particleColour);
}