audio/visualizer: store positive and negative values separately

shader/audio/resampler.comp

@@ -3,7 +3,7 @@
 layout (local_size_x = 128, local_size_y = 1, local_size_z = 1) in;
 
 layout (r16i, binding = 0) readonly uniform iimageBuffer ImageIn;
-layout (r16i, binding = 1) writeonly uniform iimageBuffer ImageOut;
+layout (rg16i, binding = 1) writeonly uniform iimageBuffer ImageOut;
 
 layout (location = 0) uniform int GlobalOffset;
 layout (location = 1) uniform int WindowLength;
@@ -14,14 +14,14 @@ void main()
 
   int offset = GlobalOffset + x * WindowLength;
 
-  float sum = 0;
-  //int sum = 0;
+  vec2 sum = vec2(0, 0);
+
   float scale = 1.0 / float(WindowLength);
   for (int i = 0; i < WindowLength; i++) {
     ivec4 v = imageLoad(ImageIn, offset + i);
-    sum += float(abs(v.x)) * scale;
-    //sum = max(abs(v.x), sum);
+    float value = float(v.x);
+    sum += vec2(clamp(value, 0.0, 32767.0), clamp(value, -32768.0, 0.0)) * scale;
   }
 
-  imageStore(ImageOut, x, ivec4(int(sum)));
+  imageStore(ImageOut, x, ivec4(int(sum.x), int(sum.y), 0, 0));
 }

shader/audio/visualizer.frag

@@ -6,21 +6,26 @@ in VS_OUT {
 
 layout (location = 0) out vec4 Color;
 
-layout (r16i, binding = 0) readonly uniform iimageBuffer Image;
+layout (rg16i, binding = 0) readonly uniform iimageBuffer Image;
 
-float get_sample(int coordinate)
+vec2 get_sample(int coordinate)
 {
-  int red = imageLoad(Image, coordinate).r;
-  return float(red) * (1.0 / 32768.0);
+  ivec2 v = imageLoad(Image, coordinate).xy;
+  return vec2(float(v.x), float(v.y)) * (1.0 / 32768.0);
 }
 
 void main()
 {
-  float value = get_sample(int(gl_FragCoord.x));
+  vec2 v = get_sample(int(gl_FragCoord.x));
 
   float y = -(fs_in.Texture.y * 2 - 1);
 
-  float c = float(abs(y) < abs(value));
+  float c;
+  if (y > 0) {
+    c = float(y < v.x);
+  } else {
+    c = float(y > v.y);
+  }
 
   Color = vec4(c, 0, 0, 1);
 }

src/audio/resampler.cpp

@@ -68,7 +68,7 @@ namespace audio::resampler {
     */
 
     // output
-    int output_size = max_output_pixels * 2;
+    int output_size = max_output_pixels * 2 * 2;
     glGenBuffers(1, &output.buffer);
     glGenTextures(1, &output.texture);
     glBindBuffer(GL_TEXTURE_BUFFER, output.buffer);
@@ -76,7 +76,7 @@ namespace audio::resampler {
     glBindBuffer(GL_TEXTURE_BUFFER, 0);
 
     glBindTexture(GL_TEXTURE_BUFFER, output.texture);
-    glTexBuffer(GL_TEXTURE_BUFFER, GL_R16I, output.buffer);
+    glTexBuffer(GL_TEXTURE_BUFFER, GL_RG16I, output.buffer);
     glBindTexture(GL_TEXTURE_BUFFER, 0);
   }
 
@@ -130,7 +130,7 @@ namespace audio::resampler {
                        GL_FALSE,
                        0,
                        GL_WRITE_ONLY,
-                       GL_R16I);
+                       GL_RG16I);
 
     int groups = window::width / local_size;
     if (groups == 0)

src/audio/visualizer.cpp

@@ -79,7 +79,7 @@ namespace audio::visualizer {
                        GL_FALSE,
                        0,
                        GL_READ_ONLY,
-                       GL_R16I);
+                       GL_RG16I);
 
     glDrawElements(GL_TRIANGLE_STRIP, 4, GL_UNSIGNED_BYTE, (void *)0);
   }