three.js/src/renderers/shaders/ShaderLib/depth.glsl.js

export const vertex = /* glsl */`
#include <common>
#include <batching_pars_vertex>
#include <uv_pars_vertex>
#include <displacementmap_pars_vertex>
#include <morphtarget_pars_vertex>
#include <skinning_pars_vertex>
#include <logdepthbuf_pars_vertex>
#include <clipping_planes_pars_vertex>

// This is used for computing an equivalent of gl_FragCoord.z that is as high precision as possible.
// Some platforms compute gl_FragCoord at a lower precision which makes the manually computed value better for
// depth-based postprocessing effects. Reproduced on iPad with A10 processor / iPadOS 13.3.1.
varying vec2 vHighPrecisionZW;

void main() {

	#include <uv_vertex>

	#include <batching_vertex>
	#include <skinbase_vertex>

	#include <morphinstance_vertex>

	#ifdef USE_DISPLACEMENTMAP

		#include <beginnormal_vertex>
		#include <morphnormal_vertex>
		#include <skinnormal_vertex>

	#endif

	#include <begin_vertex>
	#include <morphtarget_vertex>
	#include <skinning_vertex>
	#include <displacementmap_vertex>
	#include <project_vertex>
	#include <logdepthbuf_vertex>
	#include <clipping_planes_vertex>

	vHighPrecisionZW = gl_Position.zw;

}
`;

export const fragment = /* glsl */`
#if DEPTH_PACKING == 3200

	uniform float opacity;

#endif

#include <common>
#include <packing>
#include <uv_pars_fragment>
#include <map_pars_fragment>
#include <alphamap_pars_fragment>
#include <alphatest_pars_fragment>
#include <alphahash_pars_fragment>
#include <logdepthbuf_pars_fragment>
#include <clipping_planes_pars_fragment>

varying vec2 vHighPrecisionZW;

void main() {

	vec4 diffuseColor = vec4( 1.0 );
	#include <clipping_planes_fragment>

	#if DEPTH_PACKING == 3200

		diffuseColor.a = opacity;

	#endif

	#include <map_fragment>
	#include <alphamap_fragment>
	#include <alphatest_fragment>
	#include <alphahash_fragment>

	#include <logdepthbuf_fragment>

	// Higher precision equivalent of gl_FragCoord.z. This assumes depthRange has been left to its default values.
	float fragCoordZ = 0.5 * vHighPrecisionZW[0] / vHighPrecisionZW[1] + 0.5;

	#if DEPTH_PACKING == 3200

		gl_FragColor = vec4( vec3( 1.0 - fragCoordZ ), opacity );

	#elif DEPTH_PACKING == 3201

		gl_FragColor = packDepthToRGBA( fragCoordZ );

	#elif DEPTH_PACKING == 3202

		gl_FragColor = vec4( packDepthToRGB( fragCoordZ ), 1.0 );

	#elif DEPTH_PACKING == 3203

		gl_FragColor = vec4( packDepthToRG( fragCoordZ ), 0.0, 1.0 );

	#endif

}
`;