Differential D27984 Diff 77539 src/scenegraph/shadowedborderrectangle.frag

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src/scenegraph/shadowedborderrectangle.frag

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		1		/*
		2		* SPDX-FileCopyrightText: 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
		3		*
		4		* SPDX-License-Identifier: LGPL-2.0-or-later
		5		*/
		6
		7		#line 7
		8
		9		// This is based on the 2D SDF functions provided by Inigo Quilez:
		10		// https://iquilezles.org/www/articles/distfunctions2d/distfunctions2d.htm
		11
		12		// This shader renders a rectangle with rounded corners and a shadow below it.
		13		// In addition it renders a border around it.
		14
		15		uniform lowp float opacity;
		16		uniform lowp float size;
		17		uniform lowp float radius;
		18		uniform lowp vec4 color;
		19		uniform lowp vec4 shadowColor;
		20		uniform lowp vec2 offset;
		21		uniform lowp vec2 aspect;
		22		uniform lowp float borderWidth;
		23		uniform lowp vec4 borderColor;
		24
		25		varying lowp vec2 uv;
		26
		27		const lowp float minimum_shadow_radius = 0.05;
		28		const lowp float smoothing = 0.001;
		29
		30		// Calculate the distance to a rectangle with rounded corners.
		31		// \param point The point to calculate the distance of.
		32		// \param rect The rectangle to calculate the distance of.
		33		// \param translation The amount of translation to apply to the rectangle.
		34		// \param radius A vec4 with the radius of each corner. Order is top right, bottom right, top left, bottom left.
		35		lowp float sdf_rounded_rectangle(in lowp vec2 point, in lowp vec2 rect, in lowp vec2 translation, in lowp vec4 radius)
		36		{
		37		radius.xy = (point.x > 0.0) ? radius.xy : radius.zw;
		38		radius.x = (point.y > 0.0) ? radius.x : radius.y;
		39		lowp vec2 d = abs(point - translation) - rect + radius.x;
		40		return min(max(d.x, d.y), 0.0) + length(max(d, 0.0)) - radius.x;
		41		}
		42
		43		// Render an sdf value into a color.
		44		lowp vec4 sdf_render(in lowp float sdf, in lowp vec4 sourceColor, in lowp vec4 sdfColor, in lowp float sdfAlpha)
		45		{
		46		lowp float g = fwidth(sdf);
		47		return mix(sourceColor, sdfColor, sdfAlpha * (1.0 - smoothstep(smoothing - g, smoothing + g, sdf)));
		48		}
		49
		50		void main()
		51		{
		52		// Scaling factor that is the inverse of the amount of scaling applied to the geometry.
		53		lowp float inverse_scale = 1.0 / (1.0 + size + length(offset) * 2.0 + borderWidth * 2.0);
		54
		55		// Correction factor to round the corners of a larger shadow.
		56		// We want to account for size in regards to shadow radius, so that a larger shadow is
		57		// more rounded, but only if we are not already rounding the corners due to corner radius.
		58		lowp float size_factor = 0.5 * (minimum_shadow_radius / max(radius, minimum_shadow_radius));
		59
		60		lowp float shadow_radius = radius + size * size_factor;
		61
		62		lowp vec4 col = vec4(0.0);
		63
		64		// Calculate the shadow's distance field.
		65		lowp float shadow = sdf_rounded_rectangle(uv, (aspect + borderWidth) * inverse_scale, offset * inverse_scale, vec4(shadow_radius * inverse_scale));
		66		// Render it, interpolating the color over the distance.
		67		col = mix(col, shadowColor * sign(size), shadowColor.a * (1.0 - smoothstep(-size * 0.5, size * 0.5, shadow)));
		68
		69		// Scale corrected corner radius
		70		lowp vec4 corner_radius = vec4(radius * inverse_scale);
		71
		72		// Calculate the outer rectangle distance field.
		73		lowp float outer_rect = sdf_rounded_rectangle(uv, (aspect + borderWidth) * inverse_scale, vec2(0.0), corner_radius);
		74
		75		// First, remove anything that was rendered by the shadow if it is inside the rectangle.
		76		// This allows us to use colors with alpha without rendering artifacts.
		77		col = sdf_render(outer_rect, col, vec4(0.0), 1.0);
		78
		79		// Then, render it again but this time with the proper color and properly alpha blended.
		80		col = sdf_render(outer_rect, col, borderColor, borderColor.a);
		81
		82		// Calculate the inner rectangle distance field.
		83		// This uses a reduced corner radius because the inner corners need to be smaller than the outer corners.
		84		lowp vec4 inner_radius = vec4((radius - borderWidth) * inverse_scale);
		85		lowp float inner_rect = sdf_rounded_rectangle(uv, (aspect - borderWidth) * inverse_scale, vec2(0.0), inner_radius);
		86
		87		// Like above, but this time cut out the inner rectangle.
		88		col = sdf_render(inner_rect, col, vec4(0.0), 1.0);
		89
		90		// Finally, render the inner rectangle.
		91		col = sdf_render(inner_rect, col, color, color.a);
		92
		93		gl_FragColor = col * opacity;
		94		}