85 lines
2.8 KiB
GLSL
85 lines
2.8 KiB
GLSL
/*
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* MIT License
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* Author: Mark Allyn
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*
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* phosphor.frag — maps the single-channel phosphor energy texture to
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* the P7 colour sequence (blue → green → yellow-green → dark) and
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* applies a simple inline bloom (box-filter glow) to bright pixels.
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*
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* Coordinate system: gl_FragCoord.xy in GL viewport pixels (origin
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* bottom-left). Scope centre is passed as u_scopeCenter in the same
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* coordinate system.
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*/
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#version 330 core
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out vec4 fragColor;
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uniform sampler2D u_phosphor; // GL_R32F phosphor energy FBO
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uniform vec2 u_scopeCenter; // scope centre in GL viewport pixels (bottom-left origin)
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uniform float u_scopeRadius; // scope radius in pixels
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uniform float u_gain; // receiver gain [0,1] — scales brightness
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uniform float u_bloomStep; // UV step for bloom sample (≈ 2.5 / FBO_SIZE)
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uniform float u_bloomStrength; // additive blend weight for bloom
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// P7 energy thresholds (match settings.h)
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const float T_BLUE = 0.82;
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const float T_GREEN = 0.55;
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const float T_YGREE = 0.22;
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const float T_DARK = 0.03;
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// P7 colour anchors
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const vec3 C_BLUE = vec3(0.30, 0.70, 1.00);
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const vec3 C_GREEN = vec3(0.05, 1.00, 0.30);
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const vec3 C_YGREE = vec3(0.50, 1.00, 0.05);
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const vec3 C_YELLW = vec3(0.70, 0.70, 0.00);
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const vec3 C_BLACK = vec3(0.00, 0.00, 0.00);
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vec3 p7Color(float e) {
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if (e >= T_BLUE)
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return mix(C_GREEN, C_BLUE, (e - T_GREEN) / (T_BLUE - T_GREEN));
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if (e >= T_GREEN)
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return mix(C_YGREE, C_GREEN, (e - T_YGREE) / (T_GREEN - T_YGREE));
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if (e >= T_YGREE)
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return mix(C_YELLW, C_YGREE, (e - T_DARK ) / (T_YGREE - T_DARK ));
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if (e >= T_DARK)
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return mix(C_BLACK, C_YELLW, e / T_DARK);
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return C_BLACK;
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}
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void main() {
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// Fragment position relative to scope centre
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vec2 delta = (gl_FragCoord.xy - u_scopeCenter) / u_scopeRadius;
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float dist = length(delta);
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if (dist > 1.0) {
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fragColor = vec4(0.0); // outside scope circle — transparent black
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return;
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}
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// Map from PPI delta [-1,+1] to phosphor texture UV [0,1]
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// delta.x = east, delta.y = north (both y directions already match)
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vec2 uv = delta * 0.5 + 0.5;
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float energy = texture(u_phosphor, uv).r * u_gain;
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// Inline bloom: weighted box-filter over a 5×5 neighbourhood
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float bloom = 0.0;
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float wsum = 0.0;
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for (int dx = -2; dx <= 2; dx++) {
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for (int dy = -2; dy <= 2; dy++) {
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float w = exp(-float(dx*dx + dy*dy) * 0.45);
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float e = texture(u_phosphor, uv + vec2(dx, dy) * u_bloomStep).r;
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bloom += e * w;
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wsum += w;
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}
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}
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bloom = (bloom / wsum) * u_bloomStrength;
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float finalE = clamp(energy + bloom, 0.0, 1.0);
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vec3 col = p7Color(finalE);
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// Soft-edge vignette at the scope boundary
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float edge = smoothstep(1.0, 0.97, dist);
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fragColor = vec4(col * edge, 1.0);
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}
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