OpenGL Transformation 几何变换的顺序概要(MVP,NDC,Window坐标变换过程)

OpenGL Transformation 几何变换的顺序概要(MVP,NDC,Window坐标变换过程)

Geometry transforming or culling sequence:

• application passing the vertex pos(object space pos) to the shader program。
• transforming of clip space pos from object space pos by mulipling the MVP matrix。
  • to world space pos from object space pos by multipling the model/world matrix。 ( x w o r l d y w o r l d z w o r l d ) = M m o d e l / w o r l d ( x o b j y o b j z o b j ) \left( \begin{matrix} x_{\color{#aaaaaa}world}\\ y_{\color{#aaaaaa}world}\\ z_{\color{#aaaaaa}world} \end{matrix} \right)= M_{\color{#aaaaaa}model/world} \left( \begin{matrix} x_{\color{#aaaaaa}obj}\\ y_{\color{#aaaaaa}obj}\\ z_{\color{#aaaaaa}obj} \end{matrix} \right) ​xworld​yworld​zworld​​ ​=Mmodel/world​ ​xobj​yobj​zobj​​ ​
  • to view space pos from world space pos by multipling the view/camera/eye matrix。
    • right-hand coordinates ( x e y e y e y e z e y e ) = M m o d e l V i e w ( x o b j y o b j z o b j ) = M v i e w ⋅ M m o d e l / w o r l d ( x o b j y o b j z o b j ) \left( \begin{matrix} x_{\color{#aaaaaa}eye}\\ y_{\color{#aaaaaa}eye}\\ z_{\color{#aaaaaa}eye} \end{matrix} \right)= M_{\color{#aaaaaa}modelView} \left( \begin{matrix} x_{\color{#aaaaaa}obj}\\ y_{\color{#aaaaaa}obj}\\ z_{\color{#aaaaaa}obj} \end{matrix} \right)= M_{\color{#aaaaaa}view} \cdot M_{\color{#aaaaaa}model/world} \left( \begin{matrix} x_{\color{#aaaaaa}obj}\\ y_{\color{#aaaaaa}obj}\\ z_{\color{#aaaaaa}obj} \end{matrix} \right) ​xeye​yeye​zeye​​ ​=MmodelView​ ​xobj​yobj​zobj​​ ​=Mview​⋅Mmodel/world​ ​xobj​yobj​zobj​​ ​
  • to projection/clip space pos from view space pos by multipling the projective/clip matrix。 ( x c l i p y c l i p z c l i p ) = M p r o j e c t ( x e y e y e y e z e y e ) \left( \begin{matrix} x_{\color{#aaaaaa}clip}\\ y_{\color{#aaaaaa}clip}\\ z_{\color{#aaaaaa}clip} \end{matrix} \right)= M_{\color{#aaaaaa}project} \left( \begin{matrix} x_{\color{#aaaaaa}eye}\\ y_{\color{#aaaaaa}eye}\\ z_{\color{#aaaaaa}eye} \end{matrix} \right) ​xclip​yclip​zclip​​ ​=Mproject​ ​xeye​yeye​zeye​​ ​
    • culling the vertex which − w c l i p > x y z c l i p > w c l i p -w_{\color{#aaaaaa}clip}>xyz_{\color{#aaaaaa}clip}>w_{\color{#aaaaaa}clip} −wclip​>xyzclip​>wclip​。
      • add edge/vertex when culling occurs。
    • only reserve the vertex which − w c l i p < x y z c l i p < w c l i p -w_{\color{#aaaaaa}clip}