90 lines
2.6 KiB
Text
90 lines
2.6 KiB
Text
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// Fragment shader for tilt-shift effect
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// Applies gradient blur based on distance from focus line
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#extension GL_OES_EGL_image_external : require
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precision mediump float;
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// Camera texture (external texture for camera preview)
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uniform samplerExternalOES uTexture;
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// Effect parameters
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uniform float uAngle; // Rotation angle in radians
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uniform float uPosition; // Center position of focus (0-1)
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uniform float uSize; // Size of in-focus region (0-1)
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uniform float uBlurAmount; // Maximum blur intensity (0-1)
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uniform vec2 uResolution; // Texture resolution for proper sampling
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varying vec2 vTexCoord;
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// Blur kernel size (must be odd)
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const int KERNEL_SIZE = 9;
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const float KERNEL_HALF = 4.0;
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// Gaussian weights for 9-tap blur (sigma ~= 2.0)
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const float weights[9] = float[](
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0.0162, 0.0540, 0.1216, 0.1933, 0.2258,
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0.1933, 0.1216, 0.0540, 0.0162
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);
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// Calculate signed distance from the focus line
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float focusDistance(vec2 uv) {
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// Rotate coordinate system around center
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vec2 center = vec2(0.5, uPosition);
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vec2 rotated = uv - center;
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float cosA = cos(uAngle);
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float sinA = sin(uAngle);
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// After rotation, measure vertical distance from center line
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float rotatedY = -rotated.x * sinA + rotated.y * cosA;
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return abs(rotatedY);
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}
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// Calculate blur factor based on distance from focus
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float blurFactor(float dist) {
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// Smooth transition from in-focus to blurred
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float halfSize = uSize * 0.5;
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float transitionSize = halfSize * 0.5;
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if (dist < halfSize) {
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return 0.0; // In focus region
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}
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// Smooth falloff using smoothstep
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float normalizedDist = (dist - halfSize) / transitionSize;
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return smoothstep(0.0, 1.0, normalizedDist) * uBlurAmount;
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}
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// Sample with Gaussian blur
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vec4 sampleBlurred(vec2 uv, float blur) {
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if (blur < 0.01) {
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return texture2D(uTexture, uv);
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}
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vec4 color = vec4(0.0);
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vec2 texelSize = 1.0 / uResolution;
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// Blur direction perpendicular to focus line
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float blurAngle = uAngle + 1.5707963; // +90 degrees
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vec2 blurDir = vec2(cos(blurAngle), sin(blurAngle));
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// Scale blur radius by blur amount
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float radius = blur * 20.0;
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for (int i = 0; i < KERNEL_SIZE; i++) {
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float offset = (float(i) - KERNEL_HALF);
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vec2 samplePos = uv + blurDir * texelSize * offset * radius;
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color += texture2D(uTexture, samplePos) * weights[i];
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}
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return color;
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}
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void main() {
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float dist = focusDistance(vTexCoord);
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float blur = blurFactor(dist);
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gl_FragColor = sampleBlurred(vTexCoord, blur);
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}
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