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/*******************************************************************************************
*
* raylib [textures] example - screen buffer / update Image as screen buffer and display with texture
*
* Example complexity rating: [★★☆☆] 2/4
*
* Example originally created with raylib 5.5, last time updated with raylib 5.6
*
* Example contributed by Agnis Aldiņš (@nezvers) 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) 2025 Agnis Aldiņš (@nezvers)
*
********************************************************************************************/
#include "raylib.h"
#define MAX_COLORS 256
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 450
#define SCALE_FACTOR 2
// buffer size at least for screenImage pixel count
#define INDEX_BUFFER_SIZE ((SCREEN_WIDTH * SCREEN_HEIGHT) / SCALE_FACTOR)
#define FLAME_WIDTH (SCREEN_WIDTH / SCALE_FACTOR)
static void GeneretePalette(Color *palette);
static void ClearIndexBuffer(unsigned char *buffer, int count);
//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------
const int screenWidth = SCREEN_WIDTH;
const int screenHeight = SCREEN_HEIGHT;
const int pixelScale = SCALE_FACTOR;
const int imageWidth = screenWidth / pixelScale;
const int imageHeight = screenHeight / pixelScale;
InitWindow(screenWidth, screenHeight, "raylib [<module>] example - <name>");
Color palette[MAX_COLORS] = {0};
unsigned char indexBuffer[INDEX_BUFFER_SIZE] = {0};
unsigned char flameRootBuffer[FLAME_WIDTH] = {0};
Image screenImage = GenImageColor(imageWidth, imageHeight, BLACK);
Texture screenTexture = LoadTextureFromImage(screenImage);
GeneretePalette(palette);
ClearIndexBuffer(indexBuffer, INDEX_BUFFER_SIZE);
ClearIndexBuffer(flameRootBuffer, FLAME_WIDTH);
SetTargetFPS(60);
//--------------------------------------------------------------------------------------
// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
// Grow flameRoot
for (int x = 2; x < FLAME_WIDTH; ++x)
{
unsigned short flame = flameRootBuffer[x];
if (flame == 255) continue;
flame += GetRandomValue(0, 2);
if (flame > 255) flame = 255;
flameRootBuffer[x] = flame;
}
// transfer flameRoot to indexBuffer
for (int x = 0; x < FLAME_WIDTH; ++x)
{
int i = x + (imageHeight - 1) * imageWidth;
indexBuffer[i] = flameRootBuffer[x];
}
// Clear top row, because it can't move any higher
for (int x = 0; x < imageWidth; ++x)
{
if (indexBuffer[x] == 0) continue;
indexBuffer[x] = 0;
}
// Skip top row, it is already cleared
for (int y = 1; y < imageHeight; ++y)
{
for (int x = 0; x < imageWidth; ++x)
{
unsigned i = x + y * imageWidth;
unsigned char colorIndex = indexBuffer[i];
if (colorIndex == 0) continue;
// Move pixel a row above
indexBuffer[i] = 0;
int moveX = GetRandomValue(0, 2) - 1;
int newX = x + moveX;
if (newX < 0 || newX >= imageWidth) continue;
unsigned i_above = i - imageWidth + moveX;
int decay = GetRandomValue(0, 3);
colorIndex -= (decay < colorIndex) ? decay : colorIndex;
indexBuffer[i_above] = colorIndex;
}
}
// Update screenImage with palette colors
for (int y = 1; y < imageHeight; ++y)
{
for (int x = 0; x < imageWidth; ++x)
{
unsigned i = x + y * imageWidth;
unsigned char colorIndex = indexBuffer[i];
Color col = palette[colorIndex];
ImageDrawPixel(&screenImage, x, y, col);
}
}
UpdateTexture(screenTexture, screenImage.data);
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();
const Vector2 origin = (Vector2){0, 0};
const float rotation = 0.f;
DrawTextureEx(screenTexture, origin, rotation, pixelScale, WHITE);
EndDrawing();
//----------------------------------------------------------------------------------
}
// De-Initialization
//--------------------------------------------------------------------------------------
UnloadTexture(screenTexture);
UnloadImage(screenImage);
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------
return 0;
}
static void GeneretePalette(Color *palette)
{
for (int i = 0; i < MAX_COLORS; ++i)
{
float t = (float)i/(float)(MAX_COLORS - 1);
float hue = t * t;
float saturation = t;
float value = t;
palette[i] = ColorFromHSV(250.f + 150.f * hue, saturation, value);
}
}
static void ClearIndexBuffer(unsigned char *buffer, int count)
{
// Use memset to set to ZERO, but for demonstration a plain for loop is used
for (int i = 0; i < count; ++i)
{
buffer[i] = 0;
}
}