73 lines
2.4 KiB
GLSL
Executable File
73 lines
2.4 KiB
GLSL
Executable File
#version 300 es
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// Retro CRT Shader - FULLY OPTIMIZED
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// Fixes: Resolution-aware scanlines, proper vignette, edge clamping,
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// correct aberration direction, anti-aliased scanlines
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precision highp float;
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in vec2 v_texcoord;
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uniform sampler2D tex;
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out vec4 fragColor;
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// --- CONFIGURATION ---
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const float CURVATURE = 3.5;
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const float SCANLINE_STRENGTH = 0.25;
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// Approximate screen height in pixels (adjust to your resolution)
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const float SCREEN_HEIGHT = 1080.0;
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// Scanlines per screen height (lower = thicker lines)
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const float SCANLINE_COUNT = 540.0;
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const float ABERRATION = 0.002;
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const float VIGNETTE_RADIUS = 1.00;
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const float VIGNETTE_SOFTNESS = 0.45;
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// Phosphor glow simulation
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const float GLOW = 0.03;
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vec2 curveUV(vec2 uv) {
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uv = uv * 2.0 - 1.0;
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vec2 offset = abs(uv.yx) / vec2(CURVATURE);
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uv = uv + uv * offset * offset;
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uv = uv * 0.5 + 0.5;
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return uv;
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}
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void main() {
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vec2 uv = curveUV(v_texcoord);
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// Black bezel for out-of-bounds
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if (uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0) {
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fragColor = vec4(0.0, 0.0, 0.0, 1.0);
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return;
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}
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// FIXED: Clamp aberration samples to prevent edge artifacts
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vec2 centerDist = uv - 0.5;
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vec2 aberrOffset = centerDist * ABERRATION;
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// FIXED: Correct direction - red focuses short, blue focuses long
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float r = texture(tex, clamp(uv + aberrOffset, 0.0, 1.0)).r;
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float g = texture(tex, uv).g;
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float b = texture(tex, clamp(uv - aberrOffset, 0.0, 1.0)).b;
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vec3 color = vec3(r, g, b);
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// FIXED: Anti-aliased scanlines that don't shimmer during scroll
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// Using smooth triangle wave instead of harsh sine
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float scanlinePhase = uv.y * SCANLINE_COUNT * 2.0;
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float scanline = abs(fract(scanlinePhase) - 0.5) * 2.0; // Triangle wave 0-1
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scanline = smoothstep(0.0, 1.0, scanline); // Smooth it
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float scanlineFactor = 1.0 - (SCANLINE_STRENGTH * (1.0 - scanline));
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color *= scanlineFactor;
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// Subtle phosphor glow (brightens slightly between scanlines)
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color += GLOW * (1.0 - scanline);
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// FIXED: Proper circular vignette with correct smoothstep bounds
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float dist = length(centerDist) * 2.0; // 0 at center, ~1.414 at corners
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float vignette = 1.0 - smoothstep(VIGNETTE_RADIUS, VIGNETTE_RADIUS + VIGNETTE_SOFTNESS, dist);
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color *= vignette;
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// Subtle brightness boost to compensate for darkening effects
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color *= 1.1;
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fragColor = vec4(clamp(color, 0.0, 1.0), 1.0);
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}
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