import { Color, Vector3 } from 'three'; /** * God-rays (crepuscular rays) * * Similar implementation to the one used by Crytek for CryEngine 2 [Sousa2008]. * Blurs a mask generated from the depth map along radial lines emanating from the light * source. The blur repeatedly applies a blur filter of increasing support but constant * sample count to produce a blur filter with large support. * * My implementation performs 3 passes, similar to the implementation from Sousa. I found * just 6 samples per pass produced acceptible results. The blur is applied three times, * with decreasing filter support. The result is equivalent to a single pass with * 6*6*6 = 216 samples. * * References: * * Sousa2008 - Crysis Next Gen Effects, GDC2008, http://www.crytek.com/sites/default/files/GDC08_SousaT_CrysisEffects.ppt */ const GodRaysDepthMaskShader = { uniforms: { tInput: { value: null } }, vertexShader: /* glsl */` varying vec2 vUv; void main() { vUv = uv; gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 ); }`, fragmentShader: /* glsl */` varying vec2 vUv; uniform sampler2D tInput; void main() { gl_FragColor = vec4( 1.0 ) - texture2D( tInput, vUv ); }` }; /** * The god-ray generation shader. * * First pass: * * The depth map is blurred along radial lines towards the "sun". The * output is written to a temporary render target (I used a 1/4 sized * target). * * Pass two & three: * * The results of the previous pass are re-blurred, each time with a * decreased distance between samples. */ const GodRaysGenerateShader = { uniforms: { tInput: { value: null }, fStepSize: { value: 1.0 }, vSunPositionScreenSpace: { value: new Vector3() } }, vertexShader: /* glsl */` varying vec2 vUv; void main() { vUv = uv; gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 ); }`, fragmentShader: /* glsl */` #define TAPS_PER_PASS 6.0 varying vec2 vUv; uniform sampler2D tInput; uniform vec3 vSunPositionScreenSpace; uniform float fStepSize; // filter step size void main() { // delta from current pixel to "sun" position vec2 delta = vSunPositionScreenSpace.xy - vUv; float dist = length( delta ); // Step vector (uv space) vec2 stepv = fStepSize * delta / dist; // Number of iterations between pixel and sun float iters = dist/fStepSize; vec2 uv = vUv.xy; float col = 0.0; // This breaks ANGLE in Chrome 22 // - see http://code.google.com/p/chromium/issues/detail?id=153105 /* // Unrolling didnt do much on my hardware (ATI Mobility Radeon 3450), // so i've just left the loop "for ( float i = 0.0; i < TAPS_PER_PASS; i += 1.0 ) {", // Accumulate samples, making sure we dont walk past the light source. // The check for uv.y < 1 would not be necessary with "border" UV wrap // mode, with a black border color. I don't think this is currently // exposed by three.js. As a result there might be artifacts when the // sun is to the left, right or bottom of screen as these cases are // not specifically handled. " col += ( i <= iters && uv.y < 1.0 ? texture2D( tInput, uv ).r : 0.0 );", " uv += stepv;", "}", */ // Unrolling loop manually makes it work in ANGLE float f = min( 1.0, max( vSunPositionScreenSpace.z / 1000.0, 0.0 ) ); // used to fade out godrays if ( 0.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; if ( 1.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; if ( 2.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; if ( 3.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; if ( 4.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; if ( 5.0 <= iters && uv.y < 1.0 ) col += texture2D( tInput, uv ).r * f; uv += stepv; // Should technically be dividing by 'iters but 'TAPS_PER_PASS' smooths out // objectionable artifacts, in particular near the sun position. The side // effect is that the result is darker than it should be around the sun, as // TAPS_PER_PASS is greater than the number of samples actually accumulated. // When the result is inverted (in the shader 'godrays_combine this produces // a slight bright spot at the position of the sun, even when it is occluded. gl_FragColor = vec4( col/TAPS_PER_PASS ); gl_FragColor.a = 1.0; }` }; /** * Additively applies god rays from texture tGodRays to a background (tColors). * fGodRayIntensity attenuates the god rays. */ const GodRaysCombineShader = { uniforms: { tColors: { value: null }, tGodRays: { value: null }, fGodRayIntensity: { value: 0.69 } }, vertexShader: /* glsl */` varying vec2 vUv; void main() { vUv = uv; gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 ); }`, fragmentShader: /* glsl */` varying vec2 vUv; uniform sampler2D tColors; uniform sampler2D tGodRays; uniform float fGodRayIntensity; void main() { // Since THREE.MeshDepthMaterial renders foreground objects white and background // objects black, the god-rays will be white streaks. Therefore value is inverted // before being combined with tColors gl_FragColor = texture2D( tColors, vUv ) + fGodRayIntensity * vec4( 1.0 - texture2D( tGodRays, vUv ).r ); gl_FragColor.a = 1.0; }` }; /** * A dodgy sun/sky shader. Makes a bright spot at the sun location. Would be * cheaper/faster/simpler to implement this as a simple sun sprite. */ const GodRaysFakeSunShader = { uniforms: { vSunPositionScreenSpace: { value: new Vector3() }, fAspect: { value: 1.0 }, sunColor: { value: new Color( 0xffee00 ) }, bgColor: { value: new Color( 0x000000 ) } }, vertexShader: /* glsl */` varying vec2 vUv; void main() { vUv = uv; gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 ); }`, fragmentShader: /* glsl */` varying vec2 vUv; uniform vec3 vSunPositionScreenSpace; uniform float fAspect; uniform vec3 sunColor; uniform vec3 bgColor; void main() { vec2 diff = vUv - vSunPositionScreenSpace.xy; // Correct for aspect ratio diff.x *= fAspect; float prop = clamp( length( diff ) / 0.5, 0.0, 1.0 ); prop = 0.35 * pow( 1.0 - prop, 3.0 ); gl_FragColor.xyz = ( vSunPositionScreenSpace.z > 0.0 ) ? mix( sunColor, bgColor, 1.0 - prop ) : bgColor; gl_FragColor.w = 1.0; }` }; export { GodRaysDepthMaskShader, GodRaysGenerateShader, GodRaysCombineShader, GodRaysFakeSunShader };