minetest/client/shaders/blur_h/opengl_fragment.glsl

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#define rendered texture0
uniform sampler2D rendered;
uniform vec2 texelSize0;
uniform mediump float bloomRadius;
uniform mat3 bloomBlurWeights;
#ifdef GL_ES
varying mediump vec2 varTexCoord;
#else
centroid varying vec2 varTexCoord;
#endif
// smoothstep - squared
float smstsq(float f)
{
f = f * f * (3 - 2 * f);
return f;
}
void main(void)
{
// kernel distance and linear size
mediump float n = 2. * bloomRadius + 1.;
vec2 uv = varTexCoord.st - vec2(bloomRadius * texelSize0.x, 0.);
vec4 color = vec4(0.);
mediump float sum = 0.;
for (mediump float i = 0.; i < n; i++) {
mediump float weight = smstsq(1. - (abs(i / bloomRadius - 1.)));
color.rgb += texture2D(rendered, uv).rgb * weight;
sum += weight;
uv += vec2(texelSize0.x, 0.);
}
color /= sum;
gl_FragColor = vec4(color.rgb, 1.0); // force full alpha to avoid holes in the image.
}