mirror of https://github.com/axmolengine/axmol.git
42 lines
1.0 KiB
GLSL
42 lines
1.0 KiB
GLSL
#ifdef GL_ES
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precision mediump float;
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#endif
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varying vec4 v_fragmentColor;
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varying vec2 v_texCoord;
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uniform vec2 resolution;
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uniform sampler2D u_texture;
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float lookup(vec2 p, float dx, float dy)
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{
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vec2 uv = p.xy + vec2(dx , dy ) / resolution.xy;
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vec4 c = texture2D(u_texture, uv.xy);
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return 0.2126*c.r + 0.7152*c.g + 0.0722*c.b;
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}
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void main(void)
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{
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vec2 p = v_texCoord.xy;
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// simple sobel edge detection
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float gx = 0.0;
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gx += -1.0 * lookup(p, -1.0, -1.0);
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gx += -2.0 * lookup(p, -1.0, 0.0);
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gx += -1.0 * lookup(p, -1.0, 1.0);
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gx += 1.0 * lookup(p, 1.0, -1.0);
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gx += 2.0 * lookup(p, 1.0, 0.0);
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gx += 1.0 * lookup(p, 1.0, 1.0);
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float gy = 0.0;
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gy += -1.0 * lookup(p, -1.0, -1.0);
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gy += -2.0 * lookup(p, 0.0, -1.0);
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gy += -1.0 * lookup(p, 1.0, -1.0);
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gy += 1.0 * lookup(p, -1.0, 1.0);
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gy += 2.0 * lookup(p, 0.0, 1.0);
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gy += 1.0 * lookup(p, 1.0, 1.0);
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float g = gx*gx + gy*gy;
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gl_FragColor.xyz = vec3(1.-g);
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gl_FragColor.w = 1.;
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} |