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Texture

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Texture Mapping

Texture mapping demonstration animation.gif – Drummyfish – CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

https://commons.wikimedia.org/wiki/File:Texture_mapping_demonstration_animation.gif

  • Map the texture onto 3D mesh.

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Texture Coordinates

http://www.c-jump.com/bcc/common/Talk3/OpenGL/Wk07_texture/Wk07_texture.html

  • Range from 0 to 1 in the x and y axis
  • To retrieve the texture color (sampling)

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Texture Coordinates

  • Specify texture coordinate points for the 3d model
  • Pass the texture coordinates to the vertex shader & fragment shader
  • Interpolate all the texture coordinates for each fragment

https://learnopengl.com/Getting-started/Textures

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Texture Wrapping

https://learnopengl.com/Getting-started/Textures

  • When uv cordinate not in 0~1

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Texture Filtering

https://learnopengl.com/Getting-started/Textures

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Texture Filtering

Texture

Polygon

Magnification

Minification

Polygon

Texture

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Texture Filtering

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

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Mipmaps

  • Small objects with the high solution texture
  • Each subsequent texture is twice as small compared to the previous one

=> visible artifacts & waste of memory

  • Less cache memory

https://learnopengl.com/Getting-started/Textures

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Mipmaps

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

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Generating & Applying Textures

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Generating Textures

  • Read the image from file input stream and generate texture
  • Generate the texture object.
  • Bind and setup the texture object.

Fragment shader

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Reference

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