bgfx/examples/common/font/fs_font_distance_field_outline.sc

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$input v_color0, v_color1, v_texcoord0, v_texcoord1
#include "../../common/common.sh"
SAMPLERCUBE(s_texColor, 0);
uniform vec4 u_params;
#define u_distanceMultiplier u_params.y
#define u_outlineWidth u_params.w
void main()
{
vec4 color = textureCube(s_texColor, v_texcoord0.xyz);
int index = int(v_texcoord0.w*4.0 + 0.5);
float rgba[4];
rgba[0] = color.z;
rgba[1] = color.y;
rgba[2] = color.x;
rgba[3] = color.w;
float distance = rgba[index];
float smoothing = 16.0 * length(fwidth(v_texcoord0.xyz)) / sqrt(2.0) * u_distanceMultiplier;
float outlineWidth = u_outlineWidth * smoothing;
float outerEdgeCenter = 0.5 - outlineWidth;
float alpha = smoothstep(outerEdgeCenter - smoothing, outerEdgeCenter + smoothing, distance);
float border = smoothstep(0.5 - smoothing, 0.5 + smoothing, distance);
vec4 sdfColor = vec4( mix(v_color1.xyz, v_color0.xyz, border), alpha * v_color0.w );
gl_FragColor = sdfColor;
}