Add goodness color generator.

extra/color-hot.cpp

@@ -0,0 +1,64 @@
+#include <algorithm>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <math.h>
+
+inline float linear2sRGB( float v )
+{
+    float s1 = sqrt( v );
+    float s2 = sqrt( s1 );
+    float s3 = sqrt( s2 );
+    return 0.585122381f * s1 + 0.783140355f * s2 - 0.368262736f * s3;
+}
+
+float lerp( float v0, float v1, float t )
+{
+    return ( 1-t ) * v0 + t * v1;
+}
+
+inline float sRGB2linear( float v )
+{
+    return v * ( v * ( v * 0.305306011f + 0.682171111f ) + 0.012522878f );
+}
+
+int main()
+{
+    int c0 = 0x3333FF;
+    int c1 = 0x33FF33;
+
+    uint32_t t[256] = {};
+
+    float r0 = ( c0 & 0xFF ) / 255.f;
+    float r1 = ( c1 & 0xFF ) / 255.f;
+    float g0 = ( ( c0 >> 8 ) & 0xFF ) / 255.f;
+    float g1 = ( ( c1 >> 8 ) & 0xFF ) / 255.f;
+    float b0 = ( ( c0 >> 16 ) & 0xFF ) / 255.f;
+    float b1 = ( ( c1 >> 16 ) & 0xFF ) / 255.f;
+
+    for( int i=0; i<256; i++ )
+    {
+        float m = i / 255.f;
+        float rf = linear2sRGB( lerp( sRGB2linear( r0 ), sRGB2linear( r1 ), m ) );
+        float gf = linear2sRGB( lerp( sRGB2linear( g0 ), sRGB2linear( g1 ), m ) );
+        float bf = linear2sRGB( lerp( sRGB2linear( b0 ), sRGB2linear( b1 ), m ) );
+
+        int r = (int)std::clamp( rf * 255.f, 0.f, 255.f );
+        int g = (int)std::clamp( gf * 255.f, 0.f, 255.f );
+        int b = (int)std::clamp( bf * 255.f, 0.f, 255.f );
+
+        t[i] = 0xFF000000 | ( b << 16 ) | ( g << 8 ) | r;
+    }
+
+    printf( "uint32_t GoodnessColor[256] = {\n" );
+    for( int i=0; i<256; i += 8 )
+    {
+        printf( "   " );
+        for( int j=i; j<i+8; j++ )
+        {
+            printf( " 0x%X,", t[j] );
+        }
+        printf( "\n" );
+    }
+    printf( "};\n" );
+}