Implementation
var fs = [
'precision highp float;',
// Modified Blum Blum Shub pseudo-random number generator.
'vec2 mBBS( vec2 val, float modulus ) {',
'val = mod( val, modulus ); // For numerical consistancy.',
'return mod(val * val, modulus);',
'}',
// Pregenerated noise texture.
'uniform sampler2D nzw;',
'const float modulus = 61.0; // Value used in pregenerated noise texture.',
/**
* Modified noise function.
* @see http://www.csee.umbc.edu/~olano/papers/index.html#mNoise
**/
'float mnoise ( vec3 pos ) {',
'float intArg = floor( pos.z );',
'float fracArg = fract( pos.z );',
'vec2 hash = mBBS( intArg * 3.0 + vec2( 0, 3 ), modulus );',
'vec4 g = vec4 (',
'texture2D( nzw, vec2( pos.x, pos.y + hash.x ) / modulus ).xy,',
'texture2D( nzw, vec2( pos.x, pos.y + hash.y ) / modulus ).xy',
') * 2.0 - 1.0;',
'return mix(',
'g.x + g.y * fracArg,',
'g.z + g.w * ( fracArg - 1.0 ),',
'smoothstep( 0.0, 1.0, fracArg )',
');',
'}',
'const int octives = 4;',
'const float lacunarity = 2.0;',
'const float gain = 0.5;',
/**
* Adds multiple octives of noise together.
**/
'float turbulence( vec3 pos ) {',
'float sum = 0.0;',
'float freq = 1.0;',
'float amp = 1.0;',
'for ( int i = 0; i < 4; i++ ) {',
'sum += abs( mnoise( pos * freq ) ) * amp;',
'freq *= lacunarity;',
'amp *= gain;',
'}',
'return sum;',
'}',
'const float magnatude = 1.3;',
'uniform float time;',
'uniform sampler2D fireProfile;',
'uniform vec3 flamingcolor;',
/**
* Samples the fire.
*
* @param loc the normalized location (0.0-1.0) to sample the fire
* @param scale the 'size' of the fire in world space and time
**/
'vec4 sampleFire( vec3 loc, vec4 scale ) {',
// Convert xz to [-1.0, 1.0] range.
'loc.xz = loc.xz * 2.0 - 1.0;',
// Convert to (radius, height) to sample fire profile texture.
'vec2 st = vec2( sqrt( dot( loc.xz, loc.xz ) ), loc.y );',
// Convert loc to 'noise' space
'loc.y -= time * scale.w; // Scrolling noise upwards over time.',
'loc *= scale.xyz; // Scaling noise space.',
// Offsetting vertial texture lookup.
// We scale this by the sqrt of the height so that things are
// relatively stable at the base of the fire and volital at the
// top.
'float offset = sqrt( st.y ) * magnatude * turbulence( loc );',
'st.y += offset;',
// TODO: Update fireProfile texture to have a black row of pixels.
'if ( st.y > 1.0 ) {',
'return vec4( 0, 0, 0, 1 );',
'}',
'vec4 result = texture2D( fireProfile, st );',
// Fading out bottom so slice clipping isnt obvious
'if ( st.y < 0.1 ) {',
'result *= st.y / 0.1;',
'}',
'return result;',
'}',
'varying vec3 texOut;',
//'vec3 flamingcolor= vec3( 0.2,0.2,1.0 ); ',
'void main( void ) {',
// Mapping texture coordinate to -1 => 1 for xy, 0=> 1 for y
'vec3 color = sampleFire( texOut, vec4( 1.0, 2.0, 1.0, 0.5 ) ).xyz;',
//'color = vec3(0.5, 0.5, 1.0) * color; '
'color.r=color.r * flamingcolor.x;',
'color.b=color.b * flamingcolor.y;',
'color.g=color.g * flamingcolor.z;',
'gl_FragColor = vec4( color * 1.5, 1 );',
'}',
].join('\n');
