Http:// What you have to know about IGDA VIETNAM, HA NOI 17 th September 2010

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What you have to know about What you have to know about

IGDA VIETNAM, HA NOIIGDA VIETNAM, HA NOI 1717thth September 2010 September 2010


Content of the presentationContent of the presentation

• Introduction to 3D

• 3D object’s structure

• 3D Data integration

• Modeling

• Texturing/Shading

• Animation

• Tools


Introduction to 3D in gameIntroduction to 3D in game

• 3D Space description LEXICON

3D Space: Không gian 3D

Front/Back/Left/Right/Top/Bottom: Trước/Sau/Trái/Phải/Trên/Dưới

Matrix: Ma trận

Transformation: Phép biến đổi

Translation: Dịch chuyển

Rotation: Xoay

Scale: Biến đổi tỉ lệ

Vertical: Chiều ngang

Horizontal: Chiều dọc

Depth: Chiều sâu

Axis: Trục tọa độ

Coordinate: Tọa độ


Introduction to 3D in gameIntroduction to 3D in game• 3D Space description

– 3 dimensions

• X: horizontal axis

• Y: vertical axis

• Z: depth axis

– Depth buffer= Z values from view point.

– 3D Transformation Matrices


Introduction to 3D in gameIntroduction to 3D in game• View / Camera

LEXICON

View: Khung nhìn

Camera: Camera

Buffer: Bộ đệm

Local coordinates: Tọa độ địa phương

World coordinates: Tọa độ toàn cục

Clip plan: Mặt phẳng cắt – dùng để cắt bỏ các đối tượng ở quá xa

Near: Gần

Far: Xa

Render: Kết xuất

Perspective: Phối cảnh

Orthographic: Phép chiếu trực giao

Focus: Điểm hội tụ


Introduction to 3D in gameIntroduction to 3D in game• View / Camera

– Clip planes

• Near: the “screen position”

• Far: How far we can see.

– Screen coordinates based on Camera local coordinates from near clip plane. The position of the camera represents the eyes of the user in the virtual 3D world.

– Only the part of the 3D space between the clip planes is rendered and displayed on the screen.


3D object’s structure3D object’s structure• Object

– Coordinates in world space– A list of triangles that makes its surface= Mesh

LEXICON

Object: Đối tượng

Polygon: Mặt

Edge: Cạnh

Vertex/Vertices: Điểm

Surface: Bề mặt

Mesh: Đối tượng 3D dạng lưới

Hierarchy: Cây

Parent: Cha

Children: Con


3D object’s structure3D object’s structure• Polygons

– Made of triangles


3D object’s structure3D object’s structure• Triangles

– Made of 3 edges


3D object’s structure3D object’s structure• Edges

– Made of 2 vertices


3D object’s structure3D object’s structure• Vertices

– Coordinates in Object’s local reference


3D object’s structure3D object’s structure• Hierarchy (inheritance)

– Parent/Children relationship• The Parent’s coordinates are in the world’s space.

Transform the Parent will transform the Children

• The Children’s coordinates are in the Parent’s local system.

Transform a Child won’t transform the Parent.

Cap is a child of Teapot.

Cap

Teapot


3D Data integration3D Data integration• Make the game engine able to “read” the 3D data to display an object

– Check the Game Engine’s 3D format compatibilities– Choose the right 3D format to export the data: OBJ, DAE, FBX…– If you develop your own 3D data integration system you may:

• Prefer export ASCII format (text) rather than binary format: easier to read, modify and debug.

• Generate your own binary file from that to include only the required data and add game parameters (about physics, level, characters, GUI etc…).

– Example of a cube:


3D Data integration3D Data integration• OBJ format:

## object Box01#

v 0.0000 0.0000 0.0000v 0.0000 1.0000 0.0000v 1.0000 1.0000 0.0000v 1.0000 0.0000 0.0000v 0.0000 0.0000 1.0000v 1.0000 0.0000 1.0000v 1.0000 1.0000 1.0000v 0.0000 1.0000 1.0000# 8 vertices

vn 0.0000 0.0000 -1.0000vn 0.0000 0.0000 1.0000vn 0.0000 -1.0000 0.0000vn 1.0000 0.0000 0.0000vn 0.0000 1.0000 0.0000vn -1.0000 0.0000 0.0000# 6 vertex normals

vt 1.0000 0.0000 0.0000vt 1.0000 1.0000 0.0000vt 0.0000 1.0000 0.0000vt 0.0000 0.0000 0.0000# 4 texture coords

g Box01usemtl wire_154215229s 2f 1/1/1 2/2/1 3/3/1 4/4/1 s 4f 5/4/2 6/1/2 7/2/2 8/3/2 s 8f 1/4/3 4/1/3 6/2/3 5/3/3 s 16f 4/4/4 3/1/4 7/2/4 6/3/4 s 32f 3/4/5 2/1/5 8/2/5 7/3/5 s 64f 2/4/6 1/1/6 5/2/6 8/3/6 # 6 polygons


3D Data integration3D Data integration• DAE format:

…<geometry id="geom-Box01" name="Box01"> <mesh> <source id="geom-Box01-positions"> <float_array id="geom-Box01-positions-array" count="24">0 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 1 … <source id="geom-Box01-normals"> <float_array id="geom-Box01-normals-array" count="72">0 0 -1 0 0 -1 0 0 -1 0 0 -1 0 0 1 0 0 1 0 0 1 0 0 1 0 -1 0 0 -1 0 0 -1 0 0 -1 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 1 0 0 1 0 0 1 0 -1 0 0 -1 0 0 -1 0 0 -1 0 0… <source id="geom-Box01-map1"> <float_array id="geom-Box01-map1-array" count="36">0 0 0 1 0 0 0 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 1 0 <vertices id="geom-Box01-vertices"> <input semantic="POSITION" source="#geom-Box01-positions"/> </vertices> <triangles material="ColorMaterial" count="12"> <input semantic="VERTEX" source="#geom-Box01-vertices" offset="0"/> <input semantic="NORMAL" source="#geom-Box01-normals" offset="1"/> <input semantic="TEXCOORD" source="#geom-Box01-map1" offset="2" set="1"/> <p>3 0 10 1 1 8 0 2 9 0 2 9 2 3 11 3 0 10 7 4 11 6 5 10 4 6 8 4 6 8 5 7 9 7 4 11 5 8 7 4 9 6 0 10 4 0 10 4 1 11 5 5 8 7 7 12 3 5 13 2 1 14 0 1 14 0 3 15 1 7 12 3 6 16 7 7 17 6 3 18 4 3 18 4 2 19 5 6 16 7 4 20 3 6 21 2 2 22 0 2 22 0 0 23 1 4 20 3</p>…


Q&AQ&Aabout 3D object’s structureabout 3D object’s structure

3D Data integration 3D Data integration


ModelingModeling• Mesh (Vertex/Edge/Polygon)

– Transformation: translation/rotation/scale

– Modification: add/remove/copy/extrude/chamfer…

– Start modeling from a primitive: plane,cube,sphere…

LEXICON

Transformation: Phép biến đổi

Translation: Dịch chuyển

Rotation: Xoay

Scale: Biến đổi tỉ lệ

Add: Thêm

Remove: Bỏ đi

Copy: Sao chép

Extrude: Tạo khối

Chamfer: Cắt cạnh

Optimization: Tối ưu hóa

Back face culling: Khử mặt khuất

Smoothing: Làm mượt


ModelingModeling• Basic optimization

– Adapt the number of polygons to the configuration of the device.

4000 polygons 2200 polygons



– Minimum of polygon but the shape must be as good as possible.



– Back Face Culling: In most of the cases, only one face of an object’s polygon is visible. To avoid to perform rendering calculation for the “inside” face, use the “Back Face Culling”.


Q&AQ&Aabout 3D Modelingabout 3D Modeling


Texturing/ShadingTexturing/Shading• The texture

– Determine the aspect of a triangle’s surface by applying a pixel of a picture to a texel on a surface.

– It’s the most popular way to apply detailed colors on a 3D model (other type: procedural texture).

LEXICON

Texture: Là một hình ảnh dùng để áp lên bề mặt đối tượng 3D

Pixel (Picture Element): Điểm ảnh

Texel (Texture Element): Là thành tố cơ bản của texture. Một texture được cấu tạo bởi tập hợp texel, lặp đi lặp lại.

Image Resolution: Độ phân giải hình ảnh

Material: Vật liệu

Map: Thuật toán để tạo hiệu ứng bề mặt trên vật thể 3D

Diffuse color Map: Thuật toán tạo ánh sáng khuyếch tán trên bề mặt 3D

Specular Map: Thuật toán tạo ánh sáng phản chiếu trên bề mặt

Normal Map: Thuật toán tạo hiệu ứng gồ ghề trên bề mặt

Height Map: Thuật toán tạo địa hình 3D từ một tấm ảnh

Shading: Quá trình tô màu cho bề mặt 3D dựa trên góc và khoảng cách đến nguồn sáng

Shadow: Bóng đổ

Light: Ánh sáng


Texturing/ShadingTexturing/Shading• UV coordinates from an image in a 2D space mapped on a

triangle in a 3D space.


TexturingTexturing• Basic optimization

– Use sizes that are power of 2 for width and height : …,128 ,256 ,512 ,…

– Minimum size but the aspect must be as good as possible: 1 texel = 1 pixel

– Use texture tiling to repeat a texture on a large surface.


Texturing/ShadingTexturing/Shading• Material= Properties of a surface such as transparency,

roughness, softness etc… to render material like plastic, metal, wood, glass etc…


Texturing/ShadingTexturing/Shading• Basic shading

– The shading = How the light interacts with the object’s surface.



– Flat: the Light is reflected following the normal vector of each polygon as if they are separated. Very fast processing.

NORMAL VECTOR



– Gouraud: the Light is reflected following vectors from each vertex that are calculated by making an average of the normal vector of each polygon. Fast processing.

NORMAL VECTOR

Henri Gouraud (1944): French computer scientist, inventor of Gouraud Shading. Graduated at the University of Utah.



– Phong: the Light is reflected following interpolations of the normal vector of each polygon to simulate a curved surface. Slow processing.

NORMAL VECTOR

Bùi Tường Phong (1942-1975): Vietnamese computer graphics researcher born in Hanoi and living in France, inventor of Phong Shading and Phong reflection model. Graduated at the University of Utah.


Texturing/ShadingTexturing/Shading• Advanced shading

– The Shaders: Programs that modify the 3D render by applying calculation in the GPU (Graphics Processing Unit).

– Vertex shader: Can manipulate Vertex’s position, color or Texture’s coordinates (UV).

– Geometry shader: Can add or remove vertices of a mesh.

– Pixel shader: Calculate the color of individual pixels.


Q&AQ&Aabout Texture/Shadingabout Texture/Shading


AnimationAnimation• Principles

– Time line= Set the duration of an animation.– Frame = Corresponds to the display of one image– Frame rate = How fast the frame are displayed.

It’s usually measured in frame per second (FPS)– Key Frame= Frame in which main

transformations are operated.– Frame Interpolation = Calculate intermediate

frames between two key frames following animation curves.

• Methods to animate an object:– Transform the object at key frames.– Use bones that will influence the object’s

surface.– Morphing

LEXICON

Animation: Diễn họat

Time Lime: Khung thời gian

Frame: Khung

Key frame: Khung chính

Interpolation: Nội suy

Curve: Đường cong

Bone: Xương

Rigging: Gắn xương


AnimationAnimation• 1st method:

– Transform the object at key frames.

– Arrange the animation curve.


AnimationAnimation• 2nd method:

– Create a bones structure– Apply the influence of the bones on the object surface.– Animate the bones.


AnimationAnimation• 3rd method:

– Duplicate the 3D object– Transform the vertices of the copies.– Morph the object by applying a level of similarity with each of its copies.


Q&AQ&Aabout Animationabout Animation


ToolsTools

• 3D Modeling/Animation– 3DS Max– Maya– XSI Softimage– Zbrush– Blender (free)


ToolsTools

• Texture– Photoshop– Paint Shop Pro– Painter– Gimp (free)– Or any image editor


Q&AQ&A

Documents

Http:// What you have to know about IGDA VIETNAM, HA NOI 17 th September 2010