add compute shader to auto calculate screen exposure, add SSBO impl

Editor/assets/shaders/Histogram.glsl

@@ -0,0 +1,26 @@
+#type compute
+#version 460 core
+layout(local_size_x = 16, local_size_y = 16) in;
+
+layout(binding = 0) uniform sampler2D u_SceneColor;
+layout(binding = 1, std430) buffer Histogram {
+    uint bins[64];
+};
+
+uniform float u_LogMin;
+uniform float u_LogMax;
+
+void main() {
+    ivec2 texel = ivec2(gl_GlobalInvocationID.xy);
+    ivec2 size = textureSize(u_SceneColor, 0);
+    if (texel.x >= size.x || texel.y >= size.y) return;
+
+    vec3 color = texelFetch(u_SceneColor, texel, 0).rgb;
+    float lum = max(dot(color, vec3(0.2126, 0.7152, 0.0722)), 0.0001);
+    float logLum = log2(lum);
+
+    float invLogRange = 1.0 / (u_LogMax - u_LogMin);
+    float t = (logLum - u_LogMin) * invLogRange;
+    int bin = int(clamp(t * 64.0, 0.0, 63.0));
+    atomicAdd(bins[bin], 1u);
+}