make foreground color configurable

- fsLine.glsl: remove redundant "precision highp float;"

demo/index.js

@@ -59,6 +59,7 @@ window.onload = function() {
       audio: htmlAudio,
       callback: function () { htmlAudio.play(); },
       error: function (msg) { htmlError.innerHTML = msg; },
+      color: [1/32, 1, 1/32, 1],
       background: [0, 0, 0, 1],
       swap: query.swap,
       invert: query.invert,

index.js

@@ -13,7 +13,8 @@ let shadersDict = {
     fsProgress: glslify(__dirname + '/shaders/fsProgress.glsl'),
 };
 
-let defaultBackground = [0, 0, 0, 1];
+let defaultColor = [1/32, 1, 1/32, 1],
+    defaultBackground = [0, 0, 0, 1];
 
 let audioCtx;
 
@@ -49,6 +50,7 @@ function woscope(config) {
         gl: gl,
         swap: config.swap,
         invert: config.invert,
+        color: config.color,
         lineShader: createShader(gl, shadersDict.vsLine, shadersDict.fsLine),
         blurShader: createShader(gl, shadersDict.vsBlurTranspose, shadersDict.fsBlurTranspose),
         outputShader: createShader(gl, shadersDict.vsOutput, shadersDict.fsOutput),
@@ -326,6 +328,10 @@ function drawProgress(ctx, canvas) {
         if (tmpPos && tmpPos !== -1) {
             gl.uniform1f(tmpPos, progress);
         }
+        tmpPos = gl.getUniformLocation(ctx.progressShader, 'uColor');
+        if (tmpPos && tmpPos !== -1) {
+            gl.uniform4fv(tmpPos, ctx.color || defaultColor);
+        }
     }
 
     gl.bindBuffer(gl.ARRAY_BUFFER, ctx.outQuadArray);
@@ -423,6 +429,10 @@ function drawLine(ctx, shader) {
         if (tmpPos && tmpPos !== -1) {
             gl.uniform1f(tmpPos, 1);
         }
+        tmpPos = gl.getUniformLocation(shader, 'uColor');
+        if (tmpPos && tmpPos !== -1) {
+            gl.uniform4fv(tmpPos, ctx.color || defaultColor);
+        }
     }
 
     let attribs = [];

shaders/fsLine.glsl

@@ -5,7 +5,7 @@ precision highp float;
 #define SQRT2 1.4142135623730951
 uniform float uSize;
 uniform float uIntensity;
-precision highp float;
+uniform vec4 uColor;
 varying vec4 uvl;
 float gaussian(float x, float sigma) {
     return exp(-(x * x) / (2.0 * sigma * sigma)) / (TAUR * sigma);
@@ -34,5 +34,5 @@ void main (void)
     }
     float afterglow = smoothstep(0.0, 0.33, uvl.w/2048.0);
     alpha *= afterglow * uIntensity;
-    gl_FragColor = vec4(1./32., 1.0, 1./32., alpha);
+    gl_FragColor = vec4(vec3(uColor), uColor.a * alpha);
 }

shaders/fsProgress.glsl

@@ -1,5 +1,6 @@
 precision highp float;
 uniform float uProgress;
+uniform vec4 uColor;
 varying vec2 vUV;
 float rect(vec2 p, vec2 s) {
     return max(abs(p.x)-s.x,abs(p.y)-s.y);
@@ -12,5 +13,5 @@ void main (void) {
     vec2 uv = vUV*size - c;
     float result = min(rect(uv,vec2(hw+5.,25.)),-rect(uv,vec2(hw+10.,30.)));
     result = max(result,-rect(uv-vec2(hw*(p-1.0),0.0),vec2(hw*p, 20.0)));
-    gl_FragColor = vec4(vec3(0.1, 1.0, 0.1) * clamp(result, 0.0, 1.0), 1.0);
+    gl_FragColor = uColor * clamp(result, 0.0, 1.0);
 }