Pixel-Composer/shaders/sh_edge_detect/sh_edge_detect.fsh

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//
// Simple passthrough fragment shader
//
varying vec2 v_vTexcoord;
varying vec4 v_vColour;
uniform vec2 dimension;
uniform int filter;
const mat3 sobel = mat3( -1., -2., -1.,
0., 0., 0.,
1., 2., 1);
const mat3 prewit = mat3( -1., -1., -1.,
0., 0., 0.,
1., 1., 1);
const mat3 laplac = mat3( 1., 1., 1.,
1., -8., 1.,
1., 1., 1);
#define TAU 6.28318
float bright(in vec4 col) {
return dot(col.rgb, vec3(0.2126, 0.7152, 0.0722)) * col.a;
}
void main() {
vec2 texel = vec2(1.) / dimension;
vec4 point = texture2D( gm_BaseTexture, v_vTexcoord );
vec4 hColor = vec4(0.);
vec4 vColor = vec4(0.);
for(float i = -1.; i <= 1.; i++) {
for(float j = -1.; j <= 1.; j++) {
vec2 pxs = v_vTexcoord + vec2(texel.x * i, texel.y * j);
pxs = clamp(pxs, vec2(0.), vec2(1.));
int ii = int(1. + i);
int jj = int(1. + j);
if(filter == 0) {
hColor += texture2D( gm_BaseTexture, pxs ) * sobel[jj][ii];
vColor += texture2D( gm_BaseTexture, pxs ) * sobel[ii][jj];
} else if(filter == 1) {
hColor += texture2D( gm_BaseTexture, pxs ) * prewit[jj][ii];
vColor += texture2D( gm_BaseTexture, pxs ) * prewit[ii][jj];
} else if(filter == 2) {
hColor += texture2D( gm_BaseTexture, pxs ) * laplac[jj][ii];
}
}
}
if(filter == 2)
gl_FragColor = vec4(vec3(hColor), point.a);
else
gl_FragColor = vec4(vec3(distance(hColor, vColor)), point.a);
}