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- float sdBox(in vec2 p, in vec2 xy, in vec2 b)
- {
- vec2 d = abs(p - xy) - b;
- return length(max(d, 0.0)) + min(max(d.x, d.y), 0.0);
- }
- // //Author: https://iquilezles.org/articles/distfunctions2d/
- float sdTrail(in vec2 p, in vec2 v0, in vec2 v1, in vec2 v2, in vec2 v3)
- {
- float d = dot(p - v0, p - v0);
- float s = 1.0;
- // Edge from v3 to v0
- {
- vec2 e = v3 - v0;
- vec2 w = p - v0;
- vec2 b = w - e * clamp(dot(w, e) / dot(e, e), 0.0, 1.0);
- d = min(d, dot(b, b));
- // Compute branchless boolean conditions:
- float c0 = step(0.0, p.y - v0.y); // 1 if (p.y >= v0.y)
- float c1 = 1.0 - step(0.0, p.y - v3.y); // 1 if (p.y < v3.y)
- float c2 = 1.0 - step(0.0, e.x * w.y - e.y * w.x); // 1 if (e.x*w.y > e.y*w.x)
- float allCond = c0 * c1 * c2;
- float noneCond = (1.0 - c0) * (1.0 - c1) * (1.0 - c2);
- // If either allCond or noneCond is 1, then flip factor becomes -1.
- float flip = mix(1.0, -1.0, step(0.5, allCond + noneCond));
- s *= flip;
- }
- // Edge from v0 to v1
- {
- vec2 e = v0 - v1;
- vec2 w = p - v1;
- vec2 b = w - e * clamp(dot(w, e) / dot(e, e), 0.0, 1.0);
- d = min(d, dot(b, b));
- float c0 = step(0.0, p.y - v1.y);
- float c1 = 1.0 - step(0.0, p.y - v0.y);
- float c2 = 1.0 - step(0.0, e.x * w.y - e.y * w.x);
- float allCond = c0 * c1 * c2;
- float noneCond = (1.0 - c0) * (1.0 - c1) * (1.0 - c2);
- float flip = mix(1.0, -1.0, step(0.5, allCond + noneCond));
- s *= flip;
- }
- // Edge from v1 to v2
- {
- vec2 e = v1 - v2;
- vec2 w = p - v2;
- vec2 b = w - e * clamp(dot(w, e) / dot(e, e), 0.0, 1.0);
- d = min(d, dot(b, b));
- float c0 = step(0.0, p.y - v2.y);
- float c1 = 1.0 - step(0.0, p.y - v1.y);
- float c2 = 1.0 - step(0.0, e.x * w.y - e.y * w.x);
- float allCond = c0 * c1 * c2;
- float noneCond = (1.0 - c0) * (1.0 - c1) * (1.0 - c2);
- float flip = mix(1.0, -1.0, step(0.5, allCond + noneCond));
- s *= flip;
- }
- // Edge from v2 to v3
- {
- vec2 e = v2 - v3;
- vec2 w = p - v3;
- vec2 b = w - e * clamp(dot(w, e) / dot(e, e), 0.0, 1.0);
- d = min(d, dot(b, b));
- float c0 = step(0.0, p.y - v3.y);
- float c1 = 1.0 - step(0.0, p.y - v2.y);
- float c2 = 1.0 - step(0.0, e.x * w.y - e.y * w.x);
- float allCond = c0 * c1 * c2;
- float noneCond = (1.0 - c0) * (1.0 - c1) * (1.0 - c2);
- float flip = mix(1.0, -1.0, step(0.5, allCond + noneCond));
- s *= flip;
- }
- return s * sqrt(d);
- }
- vec2 normalize(vec2 value, float isPosition) {
- return (value * 2.0 - (iResolution.xy * isPosition)) / iResolution.y;
- }
- float ParametricBlend(float t)
- {
- float sqr = t * t;
- return sqr / (2.0 * (sqr - t) + 1.0);
- }
- float antialising(float distance) {
- return 1. - smoothstep(0., normalize(vec2(2., 2.), 0.).x, distance);
- }
- float determineStartVertexFactor(vec2 a, vec2 b) {
- // Conditions using step
- float condition1 = step(b.x, a.x) * step(a.y, b.y); // a.x < b.x && a.y > b.y
- float condition2 = step(a.x, b.x) * step(b.y, a.y); // a.x > b.x && a.y < b.y
- // If neither condition is met, return 1 (else case)
- return 1.0 - max(condition1, condition2);
- }
- // red
- const vec4 TRAIL_COLOR = vec4(0.8, 0.725, 0.161, 1.0);
- const vec4 TRAIL_COLOR_ACCENT = vec4(1.0, 0., 0., 1.0);
- // custom
- //const vec4 TRAIL_COLOR = vec4(0.5, 0.625, 0.161, 1.0);
- // blue
- // const vec4 TRAIL_COLOR = vec4(0.482, 0.886, 1.0, 1.0);
- // const vec4 TRAIL_COLOR_ACCENT = vec4(0.0, 0.424, 1.0, 1.0);
- const vec4 CURRENT_CURSOR_COLOR = TRAIL_COLOR;
- const vec4 PREVIOUS_CURSOR_COLOR = TRAIL_COLOR;
- const float DURATION = 0.1;
- void mainImage(out vec4 fragColor, in vec2 fragCoord)
- {
- #if !defined(WEB)
- fragColor = texture(iChannel0, fragCoord.xy / iResolution.xy);
- #endif
- //Normalization for fragCoord to a space of -1 to 1;
- vec2 vu = normalize(fragCoord, 1.);
- vec2 offsetFactor = vec2(-.5, 0.5);
- //Normalization for cursor position and size;
- //cursor xy has the postion in a space of -1 to 1;
- //zw has the width and height
- vec4 currentCursor = vec4(normalize(iCurrentCursor.xy, 1.), normalize(iCurrentCursor.zw, 0.));
- vec4 previousCursor = vec4(normalize(iPreviousCursor.xy, 1.), normalize(iPreviousCursor.zw, 0.));
- //When drawing a parellelogram between cursors for the trail i need to determine where to start at the top-left or top-right vertex of the cursor
- float vertexFactor = determineStartVertexFactor(currentCursor.xy, previousCursor.xy);
- float invertedVertexFactor = 1.0 - vertexFactor;
- //Set every vertex of my parellogram
- vec2 v0 = vec2(currentCursor.x + currentCursor.z * vertexFactor, currentCursor.y - currentCursor.w);
- vec2 v1 = vec2(currentCursor.x + currentCursor.z * invertedVertexFactor, currentCursor.y);
- vec2 v2 = vec2(previousCursor.x + currentCursor.z * invertedVertexFactor, previousCursor.y);
- vec2 v3 = vec2(previousCursor.x + currentCursor.z * vertexFactor, previousCursor.y - previousCursor.w);
- vec4 newColor = vec4(fragColor);
- float progress = ParametricBlend(clamp((iTime - iTimeCursorChange) / DURATION, 0.0, 1.0));
- //Distance between cursors determine the total length of the parallelogram;
- float lineLength = distance(currentCursor.xy, previousCursor.xy);
- float distanceToEnd = distance(vu.xy, vec2(currentCursor.x + (currentCursor.z / 2.), currentCursor.y - (currentCursor.w / 2.)));
- float alphaModifier = distanceToEnd / (lineLength * (1.0 - progress));
- // float d2 = sdTrail(vu, v0, v1, v2, v3);
- // newColor = mix(newColor, TRAIL_COLOR_ACCENT, 1.0 - smoothstep(d2, -0.01, 0.001));
- // newColor = mix(newColor, TRAIL_COLOR, 1.0 - smoothstep(d2, -0.01, 0.001));
- // newColor = mix(newColor, TRAIL_COLOR, antialising(d2));
- float cCursorDistance = sdBox(vu, currentCursor.xy - (currentCursor.zw * offsetFactor), currentCursor.zw * 0.5);
- newColor = mix(newColor, TRAIL_COLOR_ACCENT, 1.0 - smoothstep(cCursorDistance, -0.000, 0.003 * (1. - progress)));
- newColor = mix(newColor, CURRENT_CURSOR_COLOR, 1.0 - smoothstep(cCursorDistance, -0.000, 0.003 * (1. - progress)));
- // float pCursorDistance = sdBox(vu, previousCursor.xy - (previousCursor.zw * offsetFactor), previousCursor.zw * 0.5);
- // newColor = mix(newColor, PREVIOUS_CURSOR_COLOR, antialising(pCursorDistance));
- fragColor = mix(fragColor, newColor, 1.);
- // fragColor = mix(fragColor, newColor, 1.0 - alphaModifier);
- }
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