Question about EdgeDetectionMaterial in the outline sample

zzfnohell · December 20, 2017, 3:42pm

Hello,
I can not understand why the r components are not 0.0.

from line #409
_vec4 c1 = texture2D( maskTexture, vUv + uvOffset.xy);_
_ vec4 c2 = texture2D( maskTexture, vUv - uvOffset.xy);_
_ vec4 c3 = texture2D( maskTexture, vUv + uvOffset.yw);_
_ vec4 c4 = texture2D( maskTexture, vUv - uvOffset.yw);_
_ float diff1 = (c1.r - c2.r)*0.5;_
_ float diff2 = (c3.r - c4.r)*0.5;_

In my understanding the gl_FragColor of ‘maskTexture’ is assigned in line 375
gl_FragColor = vec4(0.0, depthTest, 1.0, 1.0)

github.com

mrdoob/three.js/blob/dev/examples/js/postprocessing/OutlinePass.js#L409


			fragmentShader:
				"varying vec2 vUv;\
				uniform sampler2D maskTexture;\
				uniform vec2 texSize;\
				uniform vec3 visibleEdgeColor;\
				uniform vec3 hiddenEdgeColor;\
				\
				void main() {\n\
					vec2 invSize = 1.0 / texSize;\
					vec4 uvOffset = vec4(1.0, 0.0, 0.0, 1.0) * vec4(invSize, invSize);\
					vec4 c1 = texture2D( maskTexture, vUv + uvOffset.xy);\
					vec4 c2 = texture2D( maskTexture, vUv - uvOffset.xy);\
					vec4 c3 = texture2D( maskTexture, vUv + uvOffset.yw);\
					vec4 c4 = texture2D( maskTexture, vUv - uvOffset.yw);\
					float diff1 = (c1.r - c2.r)*0.5;\
					float diff2 = (c3.r - c4.r)*0.5;\
					float d = length( vec2(diff1, diff2) );\
					float a1 = min(c1.g, c2.g);\
					float a2 = min(c3.g, c4.g);\
					float visibilityFactor = min(a1, a2);\
					vec3 edgeColor = 1.0 - visibilityFactor > 0.001 ? visibleEdgeColor : hiddenEdgeColor;\

I see my problem. Sorry to waste your time.

jiangyh · August 7, 2018, 9:50am

Hello,I have the same question why the r components are not 0.Could you kindly tell me what’s the problem?

Topic		Replies	Views
R3F Outline Issues Questions post-processing , outline , react-three-fiber	7	1781	February 26, 2024
Fragmentshader with only texture2D results in washed out color compared to MeshBasicMaterial or any other Questions materials , shaders	1	817	October 21, 2021
Jagged sharp edges on objects when using Custom Effect Pass Questions post-processing , shaders , effect-composer	2	1330	October 18, 2021
Shader Transition effects in UV Questions textures , shaders , fragment-shader , threejs	3	593	March 31, 2023
Why is the PerspectiveCamera ineffective when using RawShaderMaterial？ Questions shaders	1	276	May 11, 2022

Question about EdgeDetectionMaterial in the outline sample

Related Topics