How can I get a cylindrical texture?

xiaomingTang · July 26, 2018, 2:35am

texture
This picture is better than my words…

prisoner849 · July 26, 2018, 5:43am

Hi!
You can use two materials. One for side, the other one for caps (top, bottom).
https://jsfiddle.net/prisoner849/ns724xw3/

marquizzo · July 26, 2018, 6:35pm

Neat! I’ve never used THREE.CylinderGeometry before…

So what’s really going on in the rendering engine here? How does one mesh map to two different textures? At first I thought it would create two separate materials, but looking at my shader editor, it looks like it’s just one!

shader
See it only says Program0, and there’s no Program1

I also see the fragment shader receives only one varying vec2 vUv and only one uniform sampler2D map;. So, what I’m trying to figure out is, where does the multiple texture mapping take place? I can’t figure out how it’s happening.

prisoner849 · July 26, 2018, 7:07pm

@marquizzo
I didn’t dig so deep
But, THREE.CylinderGeometry()/THREE.CylinderBufferGeometry() supports up to 3 materials (one for side, one for top, one for bottom) and it’s controlled by groups and their material indices (if to trust to the source code)

github.com

mrdoob/three.js/blob/0949e59f3a4978efc39d7c1366d26274b7d9af82/src/geometries/CylinderGeometry.js#L302


				indices.push( i + 1, i, c );

			}

			groupCount += 3;

		}

		// add a group to the geometry. this will ensure multi material support

		scope.addGroup( groupStart, groupCount, top === true ? 1 : 2 );

		// calculate new start value for groups

		groupStart += groupCount;

	}

}

CylinderBufferGeometry.prototype = Object.create( BufferGeometry.prototype );

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How can I get a cylindrical texture?

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