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feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

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tiger tiger tiger 2026-07-17 08:22:54 +02:00
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Examples/Shapes/TopDownLights.cs Normal file
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/*******************************************************************************************
*
* raylib [shapes] example - top down lights
*
* Example complexity rating: [★★★★] 4/4
*
* Example originally created with raylib 4.2, last time updated with raylib 4.2
*
* Example contributed by Jeffery Myers (@JeffM2501) and reviewed by Ramon Santamaria (@raysan5)
*
* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
* BSD-like license that allows static linking with closed source software
*
* Copyright (c) 2022-2025 Jeffery Myers (@JeffM2501)
*
********************************************************************************************/
using System.Numerics;
using static Raylib_cs.Raylib;
using static Raylib_cs.Raymath;
using static Raylib_cs.Rlgl;
namespace Examples.Shapes;
public partial class TopDownLights : IExample
{
private const int screenWidth = 800;
private const int screenHeight = 450;
// Custom Blend Modes
private const int RLGL_SRC_ALPHA = 0x0302;
private const int RLGL_MIN = 0x8007;
private const int RLGL_MAX = 0x8008;
private const int MAX_BOXES = 20;
private const int MAX_SHADOWS = MAX_BOXES * 3; // MAX_BOXES*3 - Each box can cast up to two shadow volumes for the edges it is away from, and one for the box itself
private const int MAX_LIGHTS = 16;
public string Name => "Shapes / Top Down Lights";
public string Title => "raylib [shapes] example - top down lights";
//----------------------------------------------------------------------------------
// Types and Structures Definition
//----------------------------------------------------------------------------------
// Shadow geometry type
private class ShadowGeometry
{
public Vector2[] vertices = new Vector2[4];
}
// Light info type
private class LightInfo
{
public bool active; // Is this light slot active?
public bool dirty; // Does this light need to be updated?
public bool valid; // Is this light in a valid position?
public Vector2 position; // Light position
public RenderTexture2D mask; // Alpha mask for the light
public float outerRadius; // The distance the light touches
public Rectangle bounds; // A cached rectangle of the light bounds to help with culling
public ShadowGeometry[] shadows = new ShadowGeometry[MAX_SHADOWS];
public int shadowCount;
public LightInfo()
{
for (int i = 0; i < MAX_SHADOWS; i++) shadows[i] = new ShadowGeometry();
}
}
//------------------------------------------------------------------------------------
// Global Variables Definition
//------------------------------------------------------------------------------------
private LightInfo[] lights;
private int boxCount;
private Rectangle[] boxes;
private Texture2D backgroundTexture;
private RenderTexture2D lightMask;
private int nextLight;
private bool showLines;
public void Init()
{
lights = new LightInfo[MAX_LIGHTS];
for (int i = 0; i < MAX_LIGHTS; i++) lights[i] = new LightInfo();
// Initialize our 'world' of boxes
boxCount = 0;
boxes = new Rectangle[MAX_BOXES];
SetupBoxes();
// Create a checkerboard ground texture
Image img = GenImageChecked(64, 64, 32, 32, Color.DarkBrown, Color.DarkGray);
backgroundTexture = LoadTextureFromImage(img);
UnloadImage(img);
// Create a global light mask to hold all the blended lights
lightMask = LoadRenderTexture(GetScreenWidth(), GetScreenHeight());
// Setup initial light
SetupLight(0, 600, 400, 300);
nextLight = 1;
showLines = false;
}
public void Update()
{
// Update
//----------------------------------------------------------------------------------
// Drag light 0
if (IsMouseButtonDown(MouseButton.Left)) MoveLight(0, GetMousePosition().X, GetMousePosition().Y);
// Make a new light
if (IsMouseButtonPressed(MouseButton.Right) && (nextLight < MAX_LIGHTS))
{
SetupLight(nextLight, GetMousePosition().X, GetMousePosition().Y, 200);
nextLight++;
}
// Toggle debug info
if (IsKeyPressed(KeyboardKey.F1)) showLines = !showLines;
// Update the lights and keep track if any were dirty so we know if we need to update the master light mask
bool dirtyLights = false;
for (int i = 0; i < MAX_LIGHTS; i++)
{
if (UpdateLight(i, boxes, boxCount)) dirtyLights = true;
}
// Update the light mask
if (dirtyLights)
{
// Build up the light mask
BeginTextureMode(lightMask);
ClearBackground(Color.Black);
// Force the blend mode to only set the alpha of the destination
SetBlendFactors(RLGL_SRC_ALPHA, RLGL_SRC_ALPHA, RLGL_MIN);
SetBlendMode(BlendMode.Custom);
// Merge in all the light masks
for (int i = 0; i < MAX_LIGHTS; i++)
{
if (lights[i].active) DrawTextureRec(lights[i].mask.Texture, new Rectangle(0, 0, (float)GetScreenWidth(), -(float)GetScreenHeight()), Vector2Zero(), Color.White);
}
DrawRenderBatchActive();
// Go back to normal blend
SetBlendMode(BlendMode.Alpha);
EndTextureMode();
}
//----------------------------------------------------------------------------------
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();
ClearBackground(Color.Black);
// Draw the tile background
DrawTextureRec(backgroundTexture, new Rectangle(0, 0, (float)GetScreenWidth(), (float)GetScreenHeight()), Vector2Zero(), Color.White);
// Overlay the shadows from all the lights
DrawTextureRec(lightMask.Texture, new Rectangle(0, 0, (float)GetScreenWidth(), -(float)GetScreenHeight()), Vector2Zero(), ColorAlpha(Color.White, showLines ? 0.75f : 1.0f));
// Draw the lights
for (int i = 0; i < MAX_LIGHTS; i++)
{
if (lights[i].active) DrawCircle((int)lights[i].position.X, (int)lights[i].position.Y, 10, (i == 0) ? Color.Yellow : Color.White);
}
if (showLines)
{
for (int s = 0; s < lights[0].shadowCount; s++)
{
DrawTriangleFan(lights[0].shadows[s].vertices, 4, Color.DarkPurple);
}
for (int b = 0; b < boxCount; b++)
{
if (CheckCollisionRecs(boxes[b], lights[0].bounds)) DrawRectangleRec(boxes[b], Color.Purple);
DrawRectangleLines((int)boxes[b].X, (int)boxes[b].Y, (int)boxes[b].Width, (int)boxes[b].Height, Color.DarkBlue);
}
DrawText("(F1) Hide Shadow Volumes", 10, 50, 10, Color.Green);
}
else
{
DrawText("(F1) Show Shadow Volumes", 10, 50, 10, Color.Green);
}
DrawFPS(screenWidth - 80, 10);
DrawText("Drag to move light #1", 10, 10, 10, Color.DarkGreen);
DrawText("Right click to add new light", 10, 30, 10, Color.DarkGreen);
EndDrawing();
//----------------------------------------------------------------------------------
}
public void Unload()
{
UnloadTexture(backgroundTexture);
UnloadRenderTexture(lightMask);
for (int i = 0; i < MAX_LIGHTS; i++)
{
if (lights[i].active) UnloadRenderTexture(lights[i].mask);
}
}
//------------------------------------------------------------------------------------
// Module Functions Definition
//------------------------------------------------------------------------------------
// Move a light and mark it as dirty so that we update it's mask next frame
private void MoveLight(int slot, float x, float y)
{
lights[slot].dirty = true;
lights[slot].position.X = x;
lights[slot].position.Y = y;
// update the cached bounds
lights[slot].bounds.X = x - lights[slot].outerRadius;
lights[slot].bounds.Y = y - lights[slot].outerRadius;
}
// Compute a shadow volume for the edge
// It takes the edge and projects it back by the light radius and turns it into a quad
private void ComputeShadowVolumeForEdge(int slot, Vector2 sp, Vector2 ep)
{
if (lights[slot].shadowCount >= MAX_SHADOWS) return;
float extension = lights[slot].outerRadius * 2;
Vector2 spVector = Vector2Normalize(Vector2Subtract(sp, lights[slot].position));
Vector2 spProjection = Vector2Add(sp, Vector2Scale(spVector, extension));
Vector2 epVector = Vector2Normalize(Vector2Subtract(ep, lights[slot].position));
Vector2 epProjection = Vector2Add(ep, Vector2Scale(epVector, extension));
lights[slot].shadows[lights[slot].shadowCount].vertices[0] = sp;
lights[slot].shadows[lights[slot].shadowCount].vertices[1] = ep;
lights[slot].shadows[lights[slot].shadowCount].vertices[2] = epProjection;
lights[slot].shadows[lights[slot].shadowCount].vertices[3] = spProjection;
lights[slot].shadowCount++;
}
// Setup a light
private void SetupLight(int slot, float x, float y, float radius)
{
lights[slot].active = true;
lights[slot].valid = false; // The light must prove it is valid
lights[slot].mask = LoadRenderTexture(GetScreenWidth(), GetScreenHeight());
lights[slot].outerRadius = radius;
lights[slot].bounds.Width = radius * 2;
lights[slot].bounds.Height = radius * 2;
MoveLight(slot, x, y);
// Force the render texture to have something in it
DrawLightMask(slot);
}
// See if a light needs to update it's mask
private bool UpdateLight(int slot, Rectangle[] boxes, int count)
{
if (!lights[slot].active || !lights[slot].dirty) return false;
lights[slot].dirty = false;
lights[slot].shadowCount = 0;
lights[slot].valid = false;
for (int i = 0; i < count; i++)
{
// Are we in a box? if so we are not valid
if (CheckCollisionPointRec(lights[slot].position, boxes[i])) return false;
// If this box is outside our bounds, we can skip it
if (!CheckCollisionRecs(lights[slot].bounds, boxes[i])) continue;
// Check the edges that are on the same side we are, and cast shadow volumes out from them
// Top
Vector2 sp = new Vector2(boxes[i].X, boxes[i].Y);
Vector2 ep = new Vector2(boxes[i].X + boxes[i].Width, boxes[i].Y);
if (lights[slot].position.Y > ep.Y) ComputeShadowVolumeForEdge(slot, sp, ep);
// Right
sp = ep;
ep.Y += boxes[i].Height;
if (lights[slot].position.X < ep.X) ComputeShadowVolumeForEdge(slot, sp, ep);
// Bottom
sp = ep;
ep.X -= boxes[i].Width;
if (lights[slot].position.Y < ep.Y) ComputeShadowVolumeForEdge(slot, sp, ep);
// Left
sp = ep;
ep.Y -= boxes[i].Height;
if (lights[slot].position.X > ep.X) ComputeShadowVolumeForEdge(slot, sp, ep);
// The box itself
lights[slot].shadows[lights[slot].shadowCount].vertices[0] = new Vector2(boxes[i].X, boxes[i].Y);
lights[slot].shadows[lights[slot].shadowCount].vertices[1] = new Vector2(boxes[i].X, boxes[i].Y + boxes[i].Height);
lights[slot].shadows[lights[slot].shadowCount].vertices[2] = new Vector2(boxes[i].X + boxes[i].Width, boxes[i].Y + boxes[i].Height);
lights[slot].shadows[lights[slot].shadowCount].vertices[3] = new Vector2(boxes[i].X + boxes[i].Width, boxes[i].Y);
lights[slot].shadowCount++;
}
lights[slot].valid = true;
DrawLightMask(slot);
return true;
}
// Draw the light and shadows to the mask for a light
private void DrawLightMask(int slot)
{
// Use the light mask
BeginTextureMode(lights[slot].mask);
ClearBackground(Color.White);
// Force the blend mode to only set the alpha of the destination
SetBlendFactors(RLGL_SRC_ALPHA, RLGL_SRC_ALPHA, RLGL_MIN);
SetBlendMode(BlendMode.Custom);
// If we are valid, then draw the light radius to the alpha mask
if (lights[slot].valid) DrawCircleGradient(lights[slot].position, lights[slot].outerRadius, ColorAlpha(Color.White, 0), Color.White);
DrawRenderBatchActive();
// Cut out the shadows from the light radius by forcing the alpha to maximum
SetBlendMode(BlendMode.Alpha);
SetBlendFactors(RLGL_SRC_ALPHA, RLGL_SRC_ALPHA, RLGL_MAX);
SetBlendMode(BlendMode.Custom);
// Draw the shadows to the alpha mask
for (int i = 0; i < lights[slot].shadowCount; i++)
{
DrawTriangleFan(lights[slot].shadows[i].vertices, 4, Color.White);
}
DrawRenderBatchActive();
// Go back to normal blend mode
SetBlendMode(BlendMode.Alpha);
EndTextureMode();
}
// Set up some boxes
private void SetupBoxes()
{
boxes[0] = new Rectangle(150, 80, 40, 40);
boxes[1] = new Rectangle(1200, 700, 40, 40);
boxes[2] = new Rectangle(200, 600, 40, 40);
boxes[3] = new Rectangle(1000, 50, 40, 40);
boxes[4] = new Rectangle(500, 350, 40, 40);
for (int i = 5; i < MAX_BOXES; i++)
{
boxes[i] = new Rectangle((float)GetRandomValue(0, GetScreenWidth()), (float)GetRandomValue(0, GetScreenHeight()), (float)GetRandomValue(10, 100), (float)GetRandomValue(10, 100));
}
boxCount = MAX_BOXES;
}
public static int Main()
{
// Initialization
//--------------------------------------------------------------------------------------
InitWindow(screenWidth, screenHeight, "raylib [shapes] example - top down lights");
SetTargetFPS(60); // Set our game to run at 60 frames-per-second
//--------------------------------------------------------------------------------------
var game = new TopDownLights();
game.Init();
// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
game.Update();
}
game.Unload();
// De-Initialization
//--------------------------------------------------------------------------------------
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}
}