REVIEWED: example: Compute shader Game-of-life

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

@@ -0,0 +1,41 @@
+#version 430
+
+// Game of Life logic shader
+
+#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 neighbourCount = 0;
+    uint x = gl_GlobalInvocationID.x;
+    uint y = gl_GlobalInvocationID.y;
+
+    neighbourCount += fetchGol(x - 1, y - 1);   // Top left
+    neighbourCount += fetchGol(x, y - 1);       // Top middle
+    neighbourCount += fetchGol(x + 1, y - 1);   // Top right
+    neighbourCount += fetchGol(x - 1, y);       // Left
+    neighbourCount += fetchGol(x + 1, y);       // Right
+    neighbourCount += fetchGol(x - 1, y + 1);   // Bottom left
+    neighbourCount += fetchGol(x, y + 1);       // Bottom middle   
+    neighbourCount += fetchGol(x + 1, y + 1);   // Bottom right
+
+    if (neighbourCount == 3) setGol(x, y, 1);
+    else if (neighbourCount == 2) setGol(x, y, fetchGol(x, y));
+    else setGol(x, y, 0);
+}

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

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+#version 430
+
+// Game of Life rendering shader
+// Just renders the content of the ssbo at binding 1 to screen
+
+#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 resolution;
+
+void main()
+{
+    ivec2 coords = ivec2(fragTexCoord*resolution);
+
+    if ((golBuffer[coords.x + coords.y*uvec2(resolution).x]) == 1) finalColor = vec4(1.0);
+    else finalColor = vec4(0.0, 0.0, 0.0, 1.0);
+}

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

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+#version 430
+
+// Game of life transfert shader
+
+#define GOL_WIDTH 768
+
+// Game Of Life Update Command
+// NOTE: matches the structure defined on main program
+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 cmdIndex = gl_GlobalInvocationID.x;
+    GolUpdateCmd cmd = commands[cmdIndex];
+
+    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);
+            }
+        }
+    }
+}