Difference between revisions of "3D Fundamentals Tutorial 9"

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(Video)
(Video)
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::- The code now renders the same scene, but has become completely configurable
 
::- The code now renders the same scene, but has become completely configurable
 
* Making a new <code>Effect</code>: Color Blending [https://youtu.be/pef2405M-os?t=8m31s 8:31]
 
* Making a new <code>Effect</code>: Color Blending [https://youtu.be/pef2405M-os?t=8m31s 8:31]
 
+
:* The <code>VertexColorEffect</code> functor will not hold a texture and return interpolated texture coordinates
 +
:* Instead, it interpolates colors operating on a <code>Vec3</code> object that holds RGB values (we encode the Vertex colors as floats)
 +
:* Cube definition now needs to hold color data of each Vertex [https://youtu.be/pef2405M-os?t=10m07s 10:07]
 +
:* We need a conversion operator and a conversion constructor to translate between the <code>Vec3</code> and <code>Color</code> representation of colors [https://youtu.be/pef2405M-os?t=11m12s 11:12]
 +
:* Changes to the <code>Pipeline</code> class: generalizing Vertex transformations (independent of the pixel shader effect) [https://youtu.be/pef2405M-os?t=11m45s 11:45]
 +
:* Adding a static function <code>GetPlain()</code> in <code>Cube.h</code> to get the Vertex colors [https://youtu.be/pef2405M-os?t=13m39s 13:39]
 +
::
 +
::<syntaxhighlight lang="cpp" line>
 +
template<class V>
 +
static IndexedTriangleList<V> GetPlain(float size = 1.0f)
 +
{...}
 +
</syntaxhighlight>
 +
:* Coding the scene class </code>CubeVertexColorScene.h</code> [https://youtu.be/pef2405M-os?t=14m13s 14:13]
 
* Making a new <code>Effect</code>: Solid Colors [https://youtu.be/pef2405M-os?t=14m47s 14:47]
 
* Making a new <code>Effect</code>: Solid Colors [https://youtu.be/pef2405M-os?t=14m47s 14:47]
 
 
* ... [https://youtu.be/pef2405M-os?t=0m20s 0:20]
 
* ... [https://youtu.be/pef2405M-os?t=0m20s 0:20]
 
* ... [https://youtu.be/pef2405M-os?t=0m20s 0:20]
 
* ... [https://youtu.be/pef2405M-os?t=0m20s 0:20]

Revision as of 20:12, 1 June 2020

In this tutorial we incorporate our first shader stage into the 3D pipeline: the pixel shader stage. We also explore some basic example pixel shaders (more heavy-duty stuff to come later).

Video

The tutorial video is on YouTube here.


  • What is a Pixel Shader and why is it used? 0:20
  • We want to make color mapping of the triangles in the rendering pipeline configurable
  • One way is to use templated function objects (functors) as "plug-in" code
  • These functors determine the color of the pixel based on their input
  • Refactoring of the gfx.PutPixel(...) function in Pipeline.h 2:04
  • This is where we are ultimately determining the color of the pixel
  • Inside the PutPixel function, we want to call a shader object that defines the coloring behavior
  • Implementation of the programmable pixel shader stage in the pipeline 3:11
  • We template the pipeline class on an <class Effect>
  • We will adjust the definition of the Vertex class depending on what effect we are using
  • We adjust gfx.PutPixel(...) to take a pixel shader object, and call the function operator with the interpolated Vertex data:
gfx.PutPixel( x,y,effect.ps( iLine ) );
  • Changes to the Pipeline class 5:37
- The Pipeline object now holds an Effect object (which holds all shader data and methods)
- Coding the Effect class 6:03
- Coding the PixelShader class 6:22
  • Putting it all together in a new CubeSkinScene.h class 7:26
- The code now renders the same scene, but has become completely configurable
  • Making a new Effect: Color Blending 8:31
  • The VertexColorEffect functor will not hold a texture and return interpolated texture coordinates
  • Instead, it interpolates colors operating on a Vec3 object that holds RGB values (we encode the Vertex colors as floats)
  • Cube definition now needs to hold color data of each Vertex 10:07
  • We need a conversion operator and a conversion constructor to translate between the Vec3 and Color representation of colors 11:12
  • Changes to the Pipeline class: generalizing Vertex transformations (independent of the pixel shader effect) 11:45
  • Adding a static function GetPlain() in Cube.h to get the Vertex colors 13:39
template<class V>
static IndexedTriangleList<V> GetPlain(float size = 1.0f)
{...}
  • Coding the scene class </code>CubeVertexColorScene.h</code> 14:13

Downloads

The GitHub repository for the tutorial code is here.

See also