Add Conway's Game of Life compute shader example. (#2088)

* Add Conway's Game of Life compute shader example.

* Fix various shaders problems, and tune command buffer size.

* Various coding convention changes.

examples/shaders/resources/shaders/glsl430/gol.glsl

@@ -0,0 +1,64 @@
+// Game of Life logic shader
+#version 430
+
+#define GOL_WIDTH 768
+
+layout (local_size_x = 16, local_size_y = 16, local_size_z = 1) in;
+
+layout(std430, binding = 1) readonly restrict buffer golLayout {
+    uint golBuffer[]; // golBuffer[x, y] = golBuffer[x + gl_NumWorkGroups.x * y]
+};
+
+layout(std430, binding = 2) writeonly restrict buffer golLayout2 {
+    uint golBufferDest[]; // golBufferDest[x, y] = golBufferDest[x + gl_NumWorkGroups.x * y]
+};
+
+#define fetchGol(x, y) ((((x) < 0) || ((y) < 0) || ((x) > GOL_WIDTH) || ((y) > GOL_WIDTH)) \
+    ? (0) \
+    : golBuffer[(x) + GOL_WIDTH * (y)])
+
+#define setGol(x, y, value) golBufferDest[(x) + GOL_WIDTH * (y)] = value
+
+void main()
+{
+    uint neighbour_count = 0;
+    uint x = gl_GlobalInvocationID.x;
+    uint y = gl_GlobalInvocationID.y;
+
+    // Top left
+    neighbour_count += fetchGol(x - 1, y - 1);
+
+    // Top middle
+    neighbour_count += fetchGol(x, y - 1);
+
+    // Top right
+    neighbour_count += fetchGol(x + 1, y - 1);
+
+    // Left
+    neighbour_count += fetchGol(x - 1, y);
+
+    // Right
+    neighbour_count += fetchGol(x + 1, y);
+
+    // Bottom left
+    neighbour_count += fetchGol(x - 1, y + 1);
+
+    // Bottom middle
+    neighbour_count += fetchGol(x, y + 1);
+
+    // Bottom right
+    neighbour_count += fetchGol(x + 1, y + 1);
+
+    if (neighbour_count == 3)
+    {
+        setGol(x, y, 1);
+    }
+    else if (neighbour_count == 2)
+    {
+        setGol(x, y, fetchGol(x, y));
+    }
+    else
+    {
+        setGol(x, y, 0);
+    }
+}

examples/shaders/resources/shaders/glsl430/gol_render.glsl

@@ -0,0 +1,34 @@
+// Game of Life rendering shader
+// Just renders the content of the ssbo at binding 1 to screen.
+#version 430
+
+#define GOL_WIDTH 768
+
+// Input vertex attributes (from vertex shader)
+in vec2 fragTexCoord;
+
+// Output fragment color
+out vec4 finalColor;
+
+// Input game of life grid.
+layout(std430, binding = 1) readonly buffer golLayout
+{
+    uint golBuffer[];
+};
+
+// Output resolution
+uniform vec2 res;
+
+void main()
+{
+    ivec2 coords = ivec2(fragTexCoord * res);
+
+    if (golBuffer[coords.x + coords.y * uvec2(res).x] == 1)
+    {
+        finalColor = vec4(1.0);
+    }
+    else
+    {
+        finalColor = vec4(0.0, 0.0, 0.0, 1.0);
+    }
+}

examples/shaders/resources/shaders/glsl430/gol_transfert.glsl

@@ -0,0 +1,54 @@
+// Game of life transfert shader.
+#version 430
+#define GOL_WIDTH 768
+
+// Structure definitions
+struct GolUpdateCmd {
+    uint x; // x coordinate of the gol command
+    uint y; // y coordinate of the gol command
+    uint w; // width of the filled zone
+    uint enabled; // whether to enable or disable zone
+};
+
+// Local compute unit size.
+layout (local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+// Output game of life grid buffer.
+layout(std430, binding = 1) buffer golBufferLayout
+{
+    uint golBuffer[]; // golBuffer[x, y] = golBuffer[x + GOL_WIDTH * y]
+};
+
+// Command buffer
+layout(std430, binding = 3) readonly restrict buffer golUpdateLayout
+{
+    uint count;
+    GolUpdateCmd commands[];
+};
+
+#define isInside(x, y) (((x) >= 0) && ((y) >= 0) && ((x) < GOL_WIDTH) && ((y) < GOL_WIDTH))
+#define getBufferIndex(x, y) ((x) + GOL_WIDTH * (y))
+
+void main()
+{
+    uint cmd_index = gl_GlobalInvocationID.x;
+    GolUpdateCmd cmd = commands[cmd_index];
+
+    for (uint x = cmd.x; x < (cmd.x + cmd.w); x++)
+    {
+        for (uint y = cmd.y; y < (cmd.y + cmd.w); y++)
+        {
+            if (isInside(x, y))
+            {
+                if (cmd.enabled != 0)
+                {
+                    atomicOr(golBuffer[getBufferIndex(x, y)], 1);
+                }
+                else
+                {
+                    atomicAnd(golBuffer[getBufferIndex(x, y)], 0);
+                }
+            }
+        }
+    }
+}

examples/shaders/shaders_compute_gol.c

@@ -0,0 +1,164 @@
+/*******************************************************************************************
+*
+*   raylib [shaders] example - Compute shaders Conway's Game of Life
+*
+*   NOTE: This example requires raylib OpenGL 4.3 versions for compute shaders support,
+*
+*   NOTE: Shaders used in this example are #version 430 (OpenGL 4.3).
+*
+*   This example has been created using raylib 4.0 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Example contributed by Teddy Astie (@tsnake41)
+*
+*   Copyright (c) 2021 Teddy Astie (@tsnake41)
+*
+********************************************************************************************/
+
+#include <stdlib.h>
+
+#include "raylib.h"
+#include "rlgl.h"
+
+// IMPORTANT: This must match gol*.glsl GOL_WIDTH constant.
+//            This must be a multiple of 16 (check golLogic compute dispatch).
+#define GOL_WIDTH 768
+
+// Maximum amount of queued draw commands (squares draw from mouse down events).
+#define MAX_BUFFERED_TRANSFERTS 48
+
+struct GolUpdateCmd
+{
+    unsigned int x; // x coordinate of the gol command
+    unsigned int y; // y coordinate of the gol command
+    unsigned int w; // width of the filled zone
+    unsigned int enabled; // whether to enable or disable zone
+};
+
+struct GolUpdateSSBO
+{
+    unsigned int count;
+    struct GolUpdateCmd commands[MAX_BUFFERED_TRANSFERTS];
+};
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    InitWindow(GOL_WIDTH, GOL_WIDTH, "raylib [shaders] example - compute shader gol");
+
+    const Vector2 resolution = { GOL_WIDTH, GOL_WIDTH };
+    unsigned int brushSize = 1;
+
+    // Game of Life logic compute shader
+    char *golLogicCode = LoadFileText("resources/shaders/glsl430/gol.glsl");
+    unsigned int golLogicShader = rlCompileShader(golLogicCode, RL_COMPUTE_SHADER);
+    unsigned int golLogicProgram = rlLoadComputeShaderProgram(golLogicShader);
+    MemFree(golLogicCode);
+
+    // Game of Life logic compute shader
+    Shader golRenderShader = LoadShader(NULL, "resources/shaders/glsl430/gol_render.glsl");
+    int resUniformLoc = GetShaderLocation(golRenderShader, "res");
+
+    // Game of Life transfert shader
+    char *golTransfertCode = LoadFileText("resources/shaders/glsl430/gol_transfert.glsl");
+    unsigned int golTransfertShader = rlCompileShader(golTransfertCode, RL_COMPUTE_SHADER);
+    unsigned int golTransfertProgram = rlLoadComputeShaderProgram(golTransfertShader);
+    MemFree(golTransfertCode);
+
+    // SSBOs
+    unsigned int ssboA = rlLoadShaderBuffer(sizeof(unsigned int) * GOL_WIDTH * GOL_WIDTH, NULL, RL_DYNAMIC_COPY);
+    unsigned int ssboB = rlLoadShaderBuffer(sizeof(unsigned int) * GOL_WIDTH * GOL_WIDTH, NULL, RL_DYNAMIC_COPY);
+
+    struct GolUpdateSSBO transfertBuffer;
+    transfertBuffer.count = 0;
+
+    int transfertSSBO = rlLoadShaderBuffer(sizeof(struct GolUpdateSSBO), NULL, RL_DYNAMIC_COPY);
+
+    // Create a white texture of the size of the window to update 
+    // each pixel of the window using the fragment shader.
+    Image whiteImage = GenImageColor(GOL_WIDTH, GOL_WIDTH, WHITE);
+    Texture whiteTex = LoadTextureFromImage(whiteImage);
+    UnloadImage(whiteImage);
+
+    while (!WindowShouldClose())
+    {
+        if (IsKeyPressed(KEY_UP))                            brushSize *= 2;
+        else if (IsKeyPressed(KEY_DOWN) && (brushSize != 1)) brushSize /= 2;
+
+        if ((IsMouseButtonDown(MOUSE_BUTTON_LEFT) || IsMouseButtonDown(MOUSE_BUTTON_RIGHT))
+            && (transfertBuffer.count < MAX_BUFFERED_TRANSFERTS))
+        {
+            // Buffer a new command
+            transfertBuffer.commands[transfertBuffer.count].x = GetMouseX();
+            transfertBuffer.commands[transfertBuffer.count].y = GetMouseY();
+            transfertBuffer.commands[transfertBuffer.count].w = brushSize;
+            transfertBuffer.commands[transfertBuffer.count].enabled = IsMouseButtonDown(MOUSE_BUTTON_LEFT);
+            transfertBuffer.count++;
+        }
+        else if (transfertBuffer.count > 0)
+        {
+            // Process transfert buffer
+
+            // Send SSBO buffer to GPU
+            rlUpdateShaderBufferElements(transfertSSBO, &transfertBuffer, sizeof(struct GolUpdateSSBO), 0);
+            // Process ssbo command
+            rlEnableShader(golTransfertProgram);
+            rlBindShaderBuffer(ssboA, 1);
+            rlBindShaderBuffer(transfertSSBO, 3);
+            rlComputeShaderDispatch(transfertBuffer.count, 1, 1); // each GPU unit will process a command
+            rlDisableShader();
+
+            transfertBuffer.count = 0;
+        }
+        else
+        {
+            // Process game of life logic
+            rlEnableShader(golLogicProgram);
+            rlBindShaderBuffer(ssboA, 1);
+            rlBindShaderBuffer(ssboB, 2);
+            rlComputeShaderDispatch(GOL_WIDTH / 16, GOL_WIDTH / 16, 1);
+            rlDisableShader();
+
+            // ssboA <-> ssboB
+            int temp = ssboA;
+            ssboA = ssboB;
+            ssboB = temp;
+        }
+
+        rlBindShaderBuffer(ssboA, 1);
+
+        BeginDrawing();
+
+        ClearBackground(BLANK);
+        SetShaderValue(golRenderShader, resUniformLoc, &resolution, SHADER_UNIFORM_VEC2);
+
+        BeginShaderMode(golRenderShader);
+        DrawTexture(whiteTex, 0, 0, WHITE);
+        EndShaderMode();
+
+        DrawFPS(0, 0);
+
+        EndDrawing();
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+    // Unload shader buffers objects.
+    rlUnloadShaderBuffer(ssboA);
+    rlUnloadShaderBuffer(ssboB);
+    rlUnloadShaderBuffer(transfertSSBO);
+
+    // Unload compute shader programs
+    rlUnloadShaderProgram(golTransfertProgram);
+    rlUnloadShaderProgram(golLogicProgram);
+
+    UnloadTexture(whiteTex);       // Unload white texture
+    UnloadShader(golRenderShader); // Unload rendering fragment shader
+
+    CloseWindow();                 // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}