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RLHeatMap.md

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RLHeatMap

RLHeatMap Animation

A heat map visualization for matrix data with color gradients.

Features

  • Configurable grid resolution
  • Multiple update modes (Replace, Accumulate, Decay)
  • Custom color gradient stops
  • Normalized input coordinates
  • GPU-accelerated rendering via textures

Constructor

RLHeatMap(Rectangle aBounds, int aCellsX, int aCellsY);

Parameters:

  • aBounds - The rectangle defining the heat map's position and size
  • aCellsX - Number of horizontal cells in the grid
  • aCellsY - Number of vertical cells in the grid

Update Modes

enum class RLHeatMapUpdateMode {
    Replace,    // New points replace old values
    Accumulate, // Points add to existing values
    Decay       // Values decay over time (exponential)
};

Style Configuration

struct RLHeatMapStyle {
    bool mShowBackground = true;
    Color mBackground{20, 22, 28, 255};
    // Optional outline
    bool mShowBorder = false;
    Color mBorderColor{40, 44, 52, 255};
    float mBorderThickness = 1.0f;
};

Methods

Configuration

Method Description
setBounds(Rectangle aBounds) Set the heat map bounds
setGrid(int aCellsX, int aCellsY) Set grid resolution
setUpdateMode(RLHeatMapUpdateMode aMode) Set update mode
setDecayHalfLifeSeconds(float aSeconds) Set decay rate (for Decay mode)
setStyle(const RLHeatMapStyle &aStyle) Apply a style configuration
setColorStops(const std::vector<Color> &aStops) Set gradient colors (3-4 stops)

Data

Method Description
bool addPoints(const std::vector<Vector2>& rPoints) Add points in normalized [-1,1] space. Returns false if rPoints is empty.
clear() Clear all data

Rendering

Method Description
update(float aDt) Update decay and texture (call each frame)
draw() const Draw the heat map

Getters

Method Description
getBounds() const Get current bounds
getCellsX() const Get horizontal cell count
getCellsY() const Get vertical cell count
getUpdateMode() const Get current update mode

Complete Example

#include "raylib.h"
#include "RLHeatMap.h"
#include <vector>
#include <cmath>

int main() {
    InitWindow(800, 600, "Heat Map Example");
    SetTargetFPS(60);

    // Define heat map area
    Rectangle lBounds = {50, 50, 700, 500};

    // Create heat map with 64x64 grid
    RLHeatMap lHeatMap(lBounds, 64, 64);

    // Set accumulate mode
    lHeatMap.setUpdateMode(RLHeatMapUpdateMode::Accumulate);

    // Set color gradient (cold to hot)
    std::vector<Color> lColors = {
        Color{0, 0, 50, 255},     // Dark blue (cold)
        Color{0, 100, 200, 255},  // Blue
        Color{255, 200, 0, 255},  // Yellow
        Color{255, 50, 0, 255}    // Red (hot)
    };
    lHeatMap.setColorStops(lColors);

    float lTime = 0.0f;

    while (!WindowShouldClose()) {
        float lDt = GetFrameTime();
        lTime += lDt;

        // Generate circular pattern of points
        std::vector<Vector2> lPoints;
        for (int i = 0; i < 100; ++i) {
            float lAngle = lTime + (float)i * 0.1f;
            float lRadius = 0.3f + 0.2f * sinf(lTime * 2.0f);
            Vector2 lPoint = {
                lRadius * cosf(lAngle),
                lRadius * sinf(lAngle)
            };
            lPoints.push_back(lPoint);
        }

        // Add points to heat map
        lHeatMap.addPoints(lPoints);

        // Update
        lHeatMap.update(lDt);

        BeginDrawing();
        ClearBackground(RAYWHITE);
        
        // Draw heat map
        lHeatMap.draw();
        
        EndDrawing();
    }

    CloseWindow();
    return 0;
}

Decay Mode Example

Use decay mode for fading heat trails:

// Enable decay mode
lHeatMap.setUpdateMode(RLHeatMapUpdateMode::Decay);

// Values halve every 0.5 seconds
lHeatMap.setDecayHalfLifeSeconds(0.5f);

// Points will gradually fade out over time

Color Gradients

Custom color gradients can have 3 or 4 stops:

// 3-stop gradient (low, mid, high)
std::vector<Color> lGradient3 = {
    Color{0, 0, 100, 255},   // Low
    Color{0, 255, 0, 255},   // Mid
    Color{255, 0, 0, 255}    // High
};

// 4-stop gradient (more control)
std::vector<Color> lGradient4 = {
    Color{0, 0, 50, 255},    // 0%
    Color{0, 100, 200, 255}, // 33%
    Color{255, 200, 0, 255}, // 66%
    Color{255, 50, 0, 255}   // 100%
};

lHeatMap.setColorStops(lGradient4);

Coordinate System

Points are added in normalized space where:

  • X ranges from -1.0 (left) to 1.0 (right)
  • Y ranges from -1.0 (bottom) to 1.0 (top)
Vector2 lCenter = {0.0f, 0.0f};      // Center of heat map
Vector2 lTopRight = {1.0f, 1.0f};    // Top-right corner
Vector2 lBottomLeft = {-1.0f, -1.0f}; // Bottom-left corner