110 lines
3.3 KiB
GLSL
110 lines
3.3 KiB
GLSL
//https://lettier.github.io/3d-game-shaders-for-beginners/screen-space-refraction.html
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//Implemented by Yvain Douard.
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#version 450
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#include "compiled.inc"
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#include "std/math.glsl"
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#include "std/gbuffer.glsl"
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uniform sampler2D tex;
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uniform sampler2D tex1;
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uniform sampler2D gbufferD;
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uniform sampler2D gbuffer0;
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uniform sampler2D gbufferD1;
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uniform sampler2D gbuffer_refraction; // ior\opacity
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uniform mat4 P;
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uniform mat3 V3;
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uniform vec2 cameraProj;
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in vec3 viewRay;
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in vec2 texCoord;
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out vec4 fragColor;
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vec3 hitCoord;
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float depth;
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const int numBinarySearchSteps = 7;
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const int maxSteps = int(ceil(1.0 / ss_refractionRayStep) * ss_refractionSearchDist);
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vec2 getProjectedCoord(const vec3 hit) {
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vec4 projectedCoord = P * vec4(hit, 1.0);
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projectedCoord.xy /= projectedCoord.w;
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projectedCoord.xy = projectedCoord.xy * 0.5 + 0.5;
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#ifdef _InvY
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projectedCoord.y = 1.0 - projectedCoord.y;
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#endif
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return projectedCoord.xy;
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}
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float getDeltaDepth(const vec3 hit) {
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depth = textureLod(gbufferD1, getProjectedCoord(hit), 0.0).r * 2.0 - 1.0;
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vec3 viewPos = getPosView(viewRay, depth, cameraProj);
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return viewPos.z - hit.z;
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}
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vec4 binarySearch(vec3 dir) {
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float ddepth;
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for (int i = 0; i < numBinarySearchSteps; i++) {
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dir *= 0.5;
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hitCoord -= dir;
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ddepth = getDeltaDepth(hitCoord);
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if (ddepth < 0.0) hitCoord += dir;
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}
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if (abs(ddepth) > ss_refractionSearchDist) return vec4(0.0);
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return vec4(getProjectedCoord(hitCoord), 0.0, 1.0);
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}
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vec4 rayCast(vec3 dir) {
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float ddepth;
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dir *= ss_refractionRayStep;
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for (int i = 0; i < maxSteps; i++) {
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hitCoord += dir;
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ddepth = getDeltaDepth(hitCoord);
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if (ddepth > 0.0)
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return binarySearch(dir);
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}
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// No hit — fallback to projecting the ray to UV space
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vec2 fallbackUV = getProjectedCoord(hitCoord);
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return vec4(fallbackUV, 0.0, 0.5); // We set .w lower to indicate fallback
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}
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void main() {
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vec4 g0 = textureLod(gbuffer0, texCoord, 0.0);
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float roughness = g0.z;
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vec4 gr = textureLod(gbuffer_refraction, texCoord, 0.0);
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float ior = gr.x;
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float opac = gr.y;
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float d = textureLod(gbufferD, texCoord, 0.0).r * 2.0 - 1.0;
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if (d == 0.0 || opac == 1.0 || ior == 1.0) {
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fragColor.rgb = textureLod(tex1, texCoord, 0.0).rgb;
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return;
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}
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vec2 enc = g0.rg;
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vec3 n;
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n.z = 1.0 - abs(enc.x) - abs(enc.y);
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n.xy = n.z >= 0.0 ? enc.xy : octahedronWrap(enc.xy);
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n = normalize(n);
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vec3 viewNormal = V3 * n;
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vec3 viewPos = getPosView(viewRay, d, cameraProj);
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vec3 refracted = refract(viewPos, viewNormal, 1.0 / ior);
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hitCoord = viewPos;
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vec3 dir = refracted * (1.0 - rand(texCoord) * ss_refractionJitter * roughness) * 2.0;
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vec4 coords = rayCast(dir);
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vec2 deltaCoords = abs(vec2(0.5, 0.5) - coords.xy);
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float screenEdgeFactor = clamp(1.0 - (deltaCoords.x + deltaCoords.y), 0.0, 1.0);
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float refractivity = 1.0 - roughness;
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float intensity = pow(refractivity, ss_refractionFalloffExp) * screenEdgeFactor * \
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clamp(-refracted.z, 0.0, 1.0) * clamp((length(viewPos - hitCoord)), 0.0, 1.0) * coords.w;
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intensity = clamp(intensity, 0.0, 1.0);
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vec3 refractionCol = textureLod(tex1, coords.xy, 0.0).rgb;
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refractionCol *= intensity;
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vec3 color = textureLod(tex, texCoord.xy, 0.0).rgb;
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fragColor.rgb = mix(refractionCol, color, opac);
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}
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