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Lighten Up! Lighting a 3D World with HLSL

Lighten Up! Lighting a 3D World with HLSL. Matt Christian http://www.insidegamer.org matt@insidegamer.org. Who am I?. Current Student University of Wisconsin – Stout Applied Mathematics and Computer Science: Software Development Associate Degree in Computer Programming

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Lighten Up! Lighting a 3D World with HLSL

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  1. Lighten Up!Lighting a 3D World with HLSL Matt Christian http://www.insidegamer.org matt@insidegamer.org

  2. Who am I? • Current Student • University of Wisconsin – Stout • Applied Mathematics and Computer Science: Software Development • Associate Degree in Computer Programming • Northcentral Technical College • Avid Gamer / Game Programmer • Gamer since age 5 • Worked with XNA, DirectX, VB (yes I wrote a game in VB 6.0)

  3. Microsoft HLSL • High Level Shader Language (HLSL) • Developed for DirectX but used in all traditional graphical APIs • DirectX 8.0 • C-style language used to manipulate graphics • Vertex Shaders • Pixel Shaders • Geometry Shaders (not covered)

  4. Why Use Shaders? • Make things pretty! • More Realistic • Shaders make use of graphics hardware and allow the CPU to be free of the majority of graphical calculations done on the GPU • “Fixed” pipeline (lighting without shaders) is being phased out • XNA’s BasicEffect

  5. Vertex Shaders • Manipulate vertices • Position, color, etc…

  6. Pixel Shaders • Manipulate each pixel • Lighting, bump mapping, post-processing

  7. Rendering Pipeline • How are shaders processed?

  8. 3D Transformations • World Transformation • Transform from model coordinates to 3D world coordinates (position, rotation, scale) • View Transformation • Transform the world to align with the camera or ‘eye’ viewing the world • Projection Transformation • Convert 3D objects to 2D screen space • World*View*Projection Transformation Matrix

  9. The Point Light - Basics • A point light is a light source sending light out from the center • 2D: Circle • 3D: Sphere • Examples • Sun • Light bulb • Almost any light

  10. Steps for Our Shader • Determine all transformations • Have light travel in a specific direction • Light contacts surface • Light surface based on distance and brightness • Blend light color with surface color/ material

  11. Light - Brightness • Brightness of a surface is determined by the angle of the light versus the normal of the surface (note:Surface Normal ) • Direct light (light directed at normal) yields a brighter surface • Perpendicular light and normal yields no light applied • Illumination = cos(theta) * brightness • Where theta is the angle between the surface normal and direction of the light • Cos(90) = 0

  12. Light – Attenuation & Falloff • Attenuation is the speed at which a light’s intensity decreases (further away receives less intense light) • While Attenuation deals with distance, a light’s falloff is the loss of intensity from the center of a light source (this slide has a falloff)

  13. DirectX and Materials • General Idea of a Material • Clear layer sitting on top of an object (may be colored) defining how a surface reflects light • Light on Surface = Illumination * Material Info * Attenuation • Material Info includes: • Diffuse – Non-shiny, reflective light (concrete) • Ambient – Reflective ambient light (all-world light) • Specular – Shiny, reflective light (apple) • Emissive – Light the object emits (crystal)

  14. Code & Demo • Effect File (.fx) • DirectX 9.0c

  15. Questions? • HLSL • DirectX • Gaming

  16. More Information • http://freespace.virgin.net/hugo.elias/graphics/x_main.htm • Very helpful site on light and perceiving light • http://msdn2.microsoft.com/en-us/library/bb509561(VS.85).aspx • MSDN HLSL Documentation • http://www.insidegamer.org/projects.aspx • My projects website, contains some shader writings • http://www.geekswithblogs.net/CodeBlog • My blog

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