Merge pull request #97 from arch1t3cht30/graph_tweaks

Anti-aliasing and better joining for the graph module

shaders/graph.glsl

@@ -13,8 +13,17 @@
 #define DRAW_OUTLINE 0
 /* 1 to draw edge highlight, 0 to disable */
 #define DRAW_HIGHLIGHT 1
+/* Whether to anti-alias the border of the graph, creating a smoother curve.
+   This may have a small impact on performance. Note that this only anti-aliases
+   the border, so that the seams between the graph and the outline and/or the
+   highlight (if present) will not be aliased.
+   Note: This requires `xroot` transparency to be enabled since it
+   relies on alpha blending with the background. */
+#define ANTI_ALIAS 0
 /* outline color */
 #define OUTLINE #262626
+/* 1 to join the two channels together in the middle, 0 to clamp both down to zero */
+#define JOIN_CHANNELS 0
 /* 1 to invert (vertically), 0 otherwise */
 #define INVERT 0
 

shaders/graph/1.frag

@@ -81,16 +81,31 @@ out vec4 fragment;
 #define TWOPI 6.28318530718
 
 float half_w;
+float middle;
+highp float pixel = 1.0F / float(screen.x);
 
-void render_side(in sampler1D tex, float idx) {
-    highp float pixel = 1.0F / float(screen.x);
+float get_line_height(in sampler1D tex, float idx) {
     float s = smooth_audio_adj(tex, audio_sz, idx / half_w, pixel);
     /* scale the data upwards so we can see it */
     s *= VSCALE;
     /* clamp far ends of the screen down to make the ends of the graph smoother */
-    s *= clamp((abs((screen.x / 2) - gl_FragCoord.x) / screen.x) * 48, 0.0F, 1.0F);
+
+    float fact = clamp((abs((screen.x / 2) - gl_FragCoord.x) / screen.x) * 48, 0.0F, 1.0F);
+    #if JOIN_CHANNELS > 0
+    fact = -2 * pow(fact, 3) + 3 * pow(fact, 2);    /* To avoid spikes */
+    s = fact * s + (1 - fact) * middle;
+    #else
+    s *= fact;
+    #endif
+
     s *= clamp((min(gl_FragCoord.x, screen.x - gl_FragCoord.x) / screen.x) * 48, 0.0F, 1.0F);
 
+    return s;
+}
+
+void render_side(in sampler1D tex, float idx) {
+    float s = get_line_height(tex, idx);
+
     /* and finally set fragment color if we are in range */
     #if INVERT > 0
     float pos = float(screen.y) - gl_FragCoord.y;
@@ -106,6 +121,9 @@ void render_side(in sampler1D tex, float idx) {
 
 void main() {
     half_w = (screen.x / 2);
+
+    middle = VSCALE * (smooth_audio_adj(audio_l, audio_sz, 1, pixel) + smooth_audio_adj(audio_r, audio_sz, 0, pixel)) / 2;
+
     if (gl_FragCoord.x < half_w) {
         render_side(audio_l, LEFT_IDX);
     } else {

shaders/graph/3.frag

@@ -0,0 +1,100 @@
+
+in vec4 gl_FragCoord;
+
+#request uniform "screen" screen
+uniform ivec2 screen; /* screen dimensions */
+
+#request uniform "prev" tex
+uniform sampler2D tex;    /* screen texture    */
+
+out vec4 fragment; /* output */
+
+#include "@graph.glsl"
+#include ":graph.glsl"
+
+/* Moves toward the border of the graph, gives the
+   y coordinate of the last colored pixel */
+float get_col_height_up(float x, float oy) {
+    float y = oy;
+    #if INVERT > 0
+    while (y >= 0) {
+    #else
+    while (y < screen.y) {
+    #endif
+        vec4 f = texelFetch(tex, ivec2(x, y), 0);
+        if (f.a <= 0) {
+            #if INVERT > 0
+            y += 1;
+            #else
+            y -= 1;
+            #endif
+            break;
+        }
+        #if INVERT > 0
+        y -= 1;
+        #else
+        y += 1;
+        #endif
+    }
+
+    return y;
+}
+
+/* Moves toward the base of the graph, gives the
+   y coordinate of the first colored pixel */
+float get_col_height_down(float x, float oy) {
+    float y = oy;
+    #if INVERT > 0
+    while (y < screen.y) {
+    #else
+    while (y >= 0) {
+    #endif
+        vec4 f = texelFetch(tex, ivec2(x, y), 0);
+        if (f.a > 0) {
+            break;
+        }
+        #if INVERT > 0
+        y += 1;
+        #else
+        y -= 1;
+        #endif
+    }
+
+    return y;
+}
+
+void main() {
+    fragment = texelFetch(tex, ivec2(gl_FragCoord.x, gl_FragCoord.y), 0);
+
+    #if ANTI_ALIAS > 0
+
+    if (fragment.a <= 0) {
+        bool left_done = false;
+        float h2;
+        float a_fact = 0;
+
+        if (texelFetch(tex, ivec2(gl_FragCoord.x - 1, gl_FragCoord.y), 0).a > 0) {
+            float h1 = get_col_height_up(gl_FragCoord.x - 1, gl_FragCoord.y);
+            h2 = get_col_height_down(gl_FragCoord.x, gl_FragCoord.y);
+            fragment = texelFetch(tex, ivec2(gl_FragCoord.x, h2), 0);
+
+            a_fact = clamp(abs((h1 - gl_FragCoord.y) / (h2 - h1)), 0.0, 1.0);
+
+            left_done = true;
+        }
+        if (texelFetch(tex, ivec2(gl_FragCoord.x + 1, gl_FragCoord.y), 0).a > 0) {
+            if (!left_done) {
+                h2 = get_col_height_down(gl_FragCoord.x, gl_FragCoord.y);
+                fragment = texelFetch(tex, ivec2(gl_FragCoord.x, h2), 0);
+            }
+            float h3 = get_col_height_up(gl_FragCoord.x + 1, gl_FragCoord.y);
+
+            a_fact = max(a_fact, clamp(abs((h3 - gl_FragCoord.y) / (h2 - h3)), 0.0, 1.0));
+        }
+        
+        fragment.a *= a_fact;
+
+    }
+
+    #endif
+}