Complete demoscene-style palsma effect

ncc/examples/fire.c

@@ -21,10 +21,6 @@ u32 palette[256];
 // Greyscale fire values
 int fire[FRAME_HEIGHT][FRAME_WIDTH];
 
-
-
-
-
 //
 // Converts a HUE to r, g or b.
 // returns float in the set [0, 1].
@@ -35,86 +31,40 @@ float hue2rgb(float p, float q, float t)
         t = t + 1;
     if (t > 1)
         t = t - 1;
-    if (t < 1.0f/6)
+    if (t < 1.0f / 6)
         return p + (q - p) * 6 * t;
-    if (t < 1.0f/2)
+    if (t < 1.0f / 2)
         return q;
-    if (t < 2.0f/3)
-        return p + (q - p) * (2.0f/3 - t) * 6;
+    if (t < 2.0f / 3)
+        return p + (q - p) * (2.0f / 3 - t) * 6;
 
     return p;
 }
 
-//
 // Converts an HSL color value to RGB. Conversion formula
 // adapted from http://en.wikipedia.org/wiki/HSL_color_space.
 // Assumes h, s, and l are contained in [0, 1] and
 // returns RGB in [0, 255].
 //
-/*
 u32 hsl_to_rgb(float h, float s, float l)
 {
     if (s == 0)
     {
         // Achromatic
-        result.r = result.g = result.b = l;
+        int c = (int)(255 * l);
+        return rgb32(c, c, c);
     }
     else
     {
-        float q = l < 0.5 ? l * (1 + s) : l + s - l * s;
+        float q = l < 0.5f ? l * (1 + s) : l + s - l * s;
         float p = 2 * l - q;
-        result.r = hue2rgb(p, q, h + 1./3) * 255;
-        result.g = hue2rgb(p, q, h) * 255;
-        result.b = hue2rgb(p, q, h - 1./3) * 255;
-    }
-
-    return result;
-}
-*/
-
-
-
 
-
-// TODO
-// Convert a color from HSL format to RGB format
-u32 hsl_to_rgb(float h, float s, float v)
-{
-	if (s < 0.01f)
-	{
-		// simple gray conversion
-        int c = (int)(v * 255.0f);
-        return rgb32(c, c, c);
-	}
-
-    // convert hue from [0, 360( to range [0,6)
-    h = h / 60.0f;
-    if (h >= 6.0f)
-        h = h - 6.0f;
-
-    // break "h" down into integer and fractional parts.
-    int i = (int)h;
-    float f = h - (float)i;
-
-    // Compute the permuted RGB values
-    int vi = (int)(f * 255.0f);
-    int p = (int)((v * (1.0f - s)) * 255.0f);
-    int q = (int)((v * (1.0f - (s * f))) * 255.0f);
-    int t = (int)((v * (1.0f - (s * (1.0f - f)))) * 255.0f);
-
-    // map v, p, q, and t into red, green, and blue values
-    if (i == 0)
-        return rgb32(vi, t, p);
-    if (i == 1)
-        return rgb32(q, vi, p);
-    if (i == 2)
-        return rgb32(p, vi, t);
-    if (i == 3)
-        return rgb32(p, q, vi);
-    if (i == 4)
-        return rgb32(t, p, vi);
-
-    return rgb32(vi, p, q);
+        return rgb32(
+            (int)(hue2rgb(p, q, h + 1.0f/3) * 255),
+            (int)(hue2rgb(p, q, h) * 255),
+            (int)(hue2rgb(p, q, h - 1.0f/3) * 255)
+        );
+    }
 }
 
 void anim_callback()
@@ -177,7 +127,11 @@ void main()
     {
         // Vary the hue through the palette
         // Hue should be between orange and red
-        palette[i] = hsl_to_rgb(360.0f / 256.0f * (float)i, 1.0f, 1.0f);
+        float x = (float)i / 255;
+        float l = x + 0.3f;
+        l = l * l;
+        if (l > 1.0f) l = 1.0f;
+        palette[i] = hsl_to_rgb(x * 0.33f, 1.0f, l);
     }
 
     window_create(FRAME_WIDTH, FRAME_HEIGHT, "Demoscene Fire Effect", 0);