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Gaming Process



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  • 1. Gaming Process - SHARAD MITRA Sr. Technical Artist Exigent Studios
  • 2. What is a GAME?  A 'game' is a structured activity, usually undertaken for enjoyment and sometimes also used as an educational tool.  A rule-based activity involving challenge to reach a goal.
  • 3. Components of Game  Goals  Rules  Conflict  Interaction  Reward
  • 4. Types Of Video Games  Arcade Games  Computer Games  Console Games  Handheld Games  Mobile Games  Online Games
  • 5. Genre Of Games  Action  Adventure  Arcade Style  Puzzle  Role Playing Games (RPG)  Strategy  Simulation (SIMS)
  • 6. Action Games  An action game requires players to use quick reflexes and timing to overcome obstacles.  They are perhaps the most basic of gaming genres, and certainly one of the broadest.  Action games tend to have gameplay with emphasis on combat.  There are many subgenres of action games, such as fighting games and first-person shooters.  Ball Games  Fighting  Maze  Pinball  Shooter  First Person Shooter (FPS)  Massive Multiplayer Online FPS  Third Person Shooter
  • 7. Adventure Games  They normally require the player to solve various puzzles by interacting with people or the environment, most often in a non- confrontational way. Prince Of Persia
  • 8. Arcade Games  Arcade games often have very short levels, simple and intuitive control schemes, and rapidly increasing difficulty.
  • 9. Puzzle Games  Puzzle games require the player to solve logic puzzles or navigate complex locations such as mazes.  This genre frequently crosses over with adventure and educational games.
  • 10. Role Playing Games (RPG)  Action/Adventure  Massive Multiplayer Online RPG
  • 11. Strategy Games  Strategy video games focus on gameplay requiring careful and skillful thinking and planning in order to achieve victory. In most strategy video games, "the player is given a godlike view of the game world, indirectly controlling the units under his command"
  • 12. Simulation Games  A simulation game is a game that contains a mixture of skill, chance, and strategy to simulate an aspect of reality, such as a stock exchange.  Construction and management simulations City Building Business simulation GOD Games Government simulations  Life simulations Biological simulation Social Simulation  Vehicle simulations Flight Racing
  • 13. General Game Modelling Guidelines Before starting to create a model in any 3D application study the concept/reference. The Reference/Concept art speaks about itself in relation to the Game it's for and the Game Engine it's designed for. You have to keep in mind following points before opening a 3D application: Art Style – Close to real or conceptual art 
  • 14. General Game Modelling Guidelines  Color Concept- It will define the loops and tris in the model  Platform (Console, PC, or other)- Some Concept art will have a different modelling methodology for different Platform because of variation of hardware availability. It usually happens with models having high details
  • 15. General Game Modelling Guidelines  Relative Size and Scale of the reference in real world and/or in relation to the game  Overall Proportion of the model in 3D perspective
  • 16. General Game Modelling Guidelines  Poly Limit- Decides the importance of every cut you place on the model  Texture Limit- Defines the important breakup in the mesh as per texture. We can use a single texture sheet or multiple textures for the same model
  • 17. General Game Modelling Guidelines  Re-usability- Instancing the model in the final scene at various locations  Camera Distance- Decides on the Vertex density and Texel Density/UV Layout
  • 18. General Game Modelling Guidelines Normal Map Generation- Major factor in deciding the mesh flow and density  What is a NORMAL? A VERTEX NORMAL at a vertex of a polyhedron is the normalized average of the surface normals of the faces that contain that vertex. A NORMAL defines which way a face or vertex is pointing. The direction of the normal indicates the front, or outer surface of the face or vertex. A Normal is used for Shading and Lighting distribution on the model.
  • 19. Normal Map Theory Normal mapping is the technique to replace the existing normals on model. It can be used to greatly enhance the appearance of a Low Poly model without using more polygons. Normal( colored as light green ) is the vector that is perpendicular to the surface and thus describes the surface's orientation. We calculate per-vertex normals on the poly model by averaging connected facet normals on each vertex.
  • 20. Normal Map Theory NORMALS CALCULATION Casting rays from the low poly model to hight poly model along the normal direction returning normals on the high poly model where the ray hits it. NORMALS GENERATION Replace the normals on the origin of the ray with the returned normals.
  • 21. Normal Map Theory NORMALS MAP CREATION The whole process creates a Normal Map that store normals directly in the RGB values of an image. The RGB values of each texel in the the normal map represent the x,y,z components of the normalized mesh normal at that texel. Instead of using interpolated vertex normals to compute the lighting, the normals from the normal map texture are used.
  • 22. The Gaming Process Example 1
  • 23. The Gaming Process Example 2
  • 24. The Gaming Process Example 3
  • 25. Basic Texturing Guide What are Texture Maps? A multidimensional image that is mapped to a multidimensional space. The most common use for maps is to improve the appearance and realism of Materials Texture mapping means the mapping of a function (Texture) onto a surface in 3-D. The domain of the function can be one, two, or three-dimensional. Uses of Texture Mapping  Surface Color - Diffuse/Color Map  Surface Irregularity - Bump Map  Specularity - Specular Map  Environmental Reflection - Reflection Map  Transparency - Transparency Map  Surface Distance - Height Map  Surface Displacement - Displacement Map  Normal Vector - Normal Map  Virtual Displacement - Parallax Map
  • 26. Types of Map Diffuse Maps Diffuse maps in represent the diffuse reflection and color of a surface. In other words they define the color and intensity of light reflected back when it strikes a surface. Bump Maps Bump mapping adds an illusion of depth and texture to images. It doesn't actually alter geometry but rather affects the shading over a surface. There are two different types of bump maps: Normal Maps and Height Maps Normal Maps Normal maps define the slope or normals of a surface. In other words, they alter the direction a surface appears to be facing.
  • 27. Types of Map Height Maps Height maps are grey-scale images that define the height of the individual pixels of a surface. They adjust the visual depth of a texture. The height of each pixel is defined by the brightness of the image. A white pixel is as high, a black pixel is as low as it gets. grey levels in between represent different heights. Specular Maps Specular maps in Doom 3 represent the specular intensity and color of highlights on a surface. In other words they define the "shinyness" and color of specular reflections. The brighter a specular map is, the more shine is applied to the final material. Color applied to a specular map tints the color of highlights.
  • 28. Types of Map Reflection Maps Reflection mapping is an efficient method of simulating a complex mirroring surface by means of a precomputed texture image. The texture is used to store the image of the environment surrounding the rendered object. There are several ways of storing the surrounding environment; the most common ones are the Spherical Environment Mapping in which a single texture contains the image of the surrounding as reflected on a mirror ball Cubic Environment Mapping in which the environment is unfolded onto the six faces of a cube and stored therefore as six square textures.
  • 29. Types of Map Transparency/Alpha Maps Alpha mapping is a technique where an image is mapped (assigned) to a 3D object, and designates certain areas of the object to be transparent or translucent. The transparency can vary in strength, based on the image texture, which can be greyscale, or the alpha channel of an RGBA image texture. Displacement Maps Displacement mapping is an alternative technique in contrast to bump mapping, normal mapping, and parallax mapping, using a procedural texture or height map to cause an effect where the actual geometric position of points over the textured surface are displaced, often along the local surface normal, according to the value the texture function evaluates to at each point on the surface.
  • 30. Types of Map Parallax Map Parallax mapping (also called offset mapping or virtual displacement mapping) is an enhancement of the bump mapping or normal mapping techniques applied to textures in 3D rendering applications. Parallax mapping is implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in tangent space (the angle relative to the surface normal) and the value of the height map at that point. This means that textures such as stone walls, will have more apparent depth and thus greater realism with less of an influence on the performance of the simulation.
  • 31. Types of Map Ambience Occlusion Map Ambient occlusion is a shading method which helps add realism to local reflection models by taking into account attenuation of light due to occlusion. Unlike local methods like Phong shading, ambient occlusion is a global method, meaning the illumination at each point is a function of other geometry in the scene. The soft appearance achieved by ambient occlusion alone is similar to the way an object appears on an overcast day.
  • 32. Seamless Textures When painting your own textures, it is sometimes desirable to be able to seamlessly tile the image over a surface. A seamless texture is a texture which can be tiled on both the sides (x,y) without any visible seam which shows that the texture has been repeated or tiled on the model. The tile edge is clearly visible The tile edge is made invisible in the center of the above image. in the center of the above image.
  • 33. Pixel A pixel is generally thought of as the smallest single component of a digital image. The pixels that compose an image are ordered as a grid (columns and rows) Each pixel consists of numbers representing magnitudes of brightness and colour. Pixels are normally arranged in a regular 2-dimensional grid, and are often represented using dots, squares, or rectangles.
  • 34. Resolution Image resolution describes the detail an image holds in terms of number of pixels. More the number of pixels in an image, more crisp and detailed the image/texture would be. In computer graphic technology, the measuring unit for pixels is PPI (pixels per inch) An image that is 2048 pixels in width and 1536 pixels in height has a total of 2048×1536 = 3,145,728 pixels or 3.1 megapixels.
  • 35. Image File Image files are standardized means of organizing and storing images. Image files are composed of either pixel or vector (geometric) data that are rasterized to pixels when displayed (with few exceptions) in a vector graphic display. Image File size Image file size—expressed as the number of bytes—increases with the number of pixels composing an image, and the colour depth of the pixels. The greater the number of rows and columns, the greater the image resolution, and the larger the file. Also, each pixel of an image increases in size when its color depth increases.
  • 36. Color Depth Color "depth" is defined by the number of bits per pixel that can be displayed on a computer screen. Data is stored in bits. Each bit represents two colors because it has a value of 0 or 1. The more bits per pixel, the more colors that can be displayed. Examples of color depth are shown in the following table: Color Depth No. of Colors Color Mode 1 bit color (21)=2 Indexed Color 4 bit color (24)=16 Indexed Color 8 bit color (28)=256 Indexed Color 16 bit color (216)=65,536 True Color 24 bit color (224)16,777,216 True Color 1 bit 4 bit 8 bit 24 bit
  • 37. True Color v/s Index Color True Color Images are known as "True Color" where each pixel is defined in terms of its actual RGB or CMYK values. Every pixel in a a true color image has 256 possible values for each of it's red, green or blue components (in the RGB model) or cyan, magenta, yellow and black (in the CMYK model). Because there are 256 possible values for each RGB or CMYK component, then RGB true color would have a 24-bit color depth and CMYK true color would have a 32-bit color depth. There are millions of possible colors for each pixel in a true color image. That's why it is called "True Color". Index Color Images which do not define colors in terms of their actual RGB or CMYK values and which derive its colors from a "palette" are known as "Indexed Color". The color palette of an indexed color image has a fixed number of colors. Because the palette is limited to a maximum of 256 colors, it is not possible for an image to look as realistic as it can using RGB or CMYK. Hence, they are not true color. This type of color is known as "Indexed Color" because colors in the palette are referenced by index numbers which are used by the computer to identify each color.
  • 38. Image File Formats  Image file types vary based on the type and amount of compression they use. Few are Lossless compression and others are Lossy compression.  A lossless compression algorithm discards no information. It looks for more efficient ways to represent an image, while making no compromises in accuracy.  In contrast, lossy algorithms accept some degradation in the image in order to achieve smaller file size. File Types PSD- (Photoshop Data) - This is the native Photoshop file format created by Adobe. In this format, you can save multiple alpha channels and paths along with your primary image. PNG- (Portable Network Graphics) - PNG is also a lossless storage format. However, in contrast with common TIFF usage, it looks for patterns in the image that it can use to compress file size. The compression is exactly reversible, so the image is recovered exactly. JPG/JPEG- (Joint Photographic Experts Group) - JPG is optimized for photographs and similar continuous tone images that contain many, many colors. The degree of compression can be adjusted, allowing a selectable trade off between storage size and image quality. - JPEG typically achieves 10 to 1 compression with little perceivable loss in image quality.
  • 39. Image File Formats TGA/TARGA- (Truevision Graphics) - Most common in the video industry, this file format is also used by high-end paint and ray-tracing programs. The TGA format has many variations and supports several types of compression. DDS- (Direct Draw Surface) - The DirectDraw Surface graphics file format was established by Microsoft for use with the DirectX SDK. The format is specifically designed for use in real-time rendering applications, such as 3D games. It can be used to store textures, cubemaps, mipmap levels, and allows for compression. Due to the fact that most video cards natively support DXTn texture compression, use of this format can save memory on the video card. When saving to DDS with mipmap levels option, the size of the image you are saving should be equal to a degree of two (128, 512, 1024 etc.). DXT Format Compression Comparison DX 10 Name Description Alpha Pre-multiplied? Compression ratio Texture Type DXT1 1-bit Alpha / Opaque N/A 8:1 Simple non-alpha DXT2 Explicit alpha Yes 4:1 Sharp alpha DXT3 Explicit alpha No 4:1 Sharp alpha DXT4 Interpolated alpha Yes 4:1 Gradient alpha DXT5 Interpolated alpha No 4:1 Gradient alpha
  • 40. Character Specific Guidelines Reference Material It is really important that you have this reference material. You may as well be modelling with your eyes closed if you don't use anything to base your model on.
  • 41. Starting Out You should also find out as much about the character as possible - * Is it an in game model or will it be used in pre-rendered cut scenes? * You will need a rough polygon count limit. * Finger amount. Will it have full fingers or a mitten type hand with no fingers? * Facial detail, will the characters face need to animate to show emotions and talk? * How many level of details (LOD's) are required?
  • 42. Muscle Structure Keep an eye on where the muscles lie on your character, placing edges along the muscle lines will result in a much more natural deformation as well as making your model look better.
  • 43. Mesh Flow It is really important to have the mesh flow (wire connections) right as per the muscle structure to get the desired result. The muscle structure will depend on the characteristic properties of the character which defines the type and variation of animation required.
  • 44. Mesh Flow Topology construction should be proper at all major joints for proper deformations during character animation.
  • 45. Face Details Face topology is very important, depending on what you wish to achieve with your model that is. A good rule, as with the body, is to stick strictly to the muscle structure when placing your polygons and edges. Paying attention to how the face creases, and constructing it according will give you a natural looking face as well as making the creation of blend shapes and animation easier and more fluid.
  • 46. Finalizing the Model  Check the POLY LIMIT specified for that model  Do a Silhouette Check on the model to finalize its proportion and curves
  • 47. Texturing Basics- Vertex  When a model is created as a polygon mesh using a 3D modeler, UV coordinates can be generated for each vertex in the mesh for texturing the model.  Vertex is a corner point of a polygon; a node in a Triangulated irregular network or TIN.  When vertices are moved or edited, the geometry they form is affected as well.
  • 48. Texturing Basics- UV Coordinates  UV coordinates are 2D coordinates that are mapped onto a 3D model. UV coordinates are a texture’s x and y coordinates and always range from 0 to 1.  The U, V, and W coordinates parallel the relative directions of X, Y, and Z coordinates.
  • 49. Texturing Basics- UVs  UVs are two-dimensional texture coordinates that reside with the vertex component information for polygonal and subdivision surface meshes. UVs exist to define a two-dimensional texture coordinate system, called UV texture space.  UV texture space uses the letters U and V to indicate the axes in 2D.  UV texture space facilitates the placement of image texture maps on a 3D surface.
  • 50. Texturing Basics- UV Mapping  The nifty thing about UV mapping is that it provides you with very literal, accurate template on which to paint your textures, particularly useful for uneven, organically structured surfaces that can't be textured using standard planar texturing methods.  We can compile the maps for a bunch of different pieces of your models into a single UV template so that you can texture all of them in one go with a single image. This is particularly important for games.
  • 51. Determining Texture Size What size is this texture going to appear on-screen?  What level of detail do we need to include in this texture?   Object Size - small size texture need small size map while large objects need large maps as they will be clearly visible on the screen Camera Distance – Placement of object in relation to camera
  • 52. Determining Texture Size  LOD's - Level Of Details we need through texture (and not through model details)  Tilability – Repetition of the texture on the model
  • 53. Determining Texture Size  Texel Density Texture quality is best described as 'texel density'. A texel, or texture element (also texture pixel) is the fundamental unit of texture space, used in computer graphics. Textures are represented by arrays of texels, just as pictures are represented by arrays of pixels. What will be the Texel density also depends whether we need tileable texture or one complete map on the model.
  • 54. Power of 2 Texture Theory Why the textures are mostly created with power of 2, i.e. , 64X64; 128x128; 256x256 and so on?  All graphic libraries has defined the texture size standard as power of 2 [D3DPTEXTURECAPS_POW2]  It is easy for any rendering engine to calculate and tile textures with POW2  UV mapping technique in all 3D applications defines the texture space in square (0,1)  Mipmapping is not supported for non-POW2 Textures  Few game engines squeeze the non square texture (128x1024) back to square texture resulting in inappropriate texture placement.
  • 55. Shaders and Materials Shader is the algorithm that controls how the material responds to light. Shaders especially control how highlights appear. They also provide a material's color components, and control its opacity, self-illumination, and other settings. Shaders are often named for their inventors; they can also be named for the effect they provide. Samples of different shading for a standard material 1. Anisotropic 2. Blinn 3. Metal 4. Multi-layer 5. Oren-Nayar-Blinn 6. Phong 7. Strauss 8. Translucent
  • 56. Shaders and Materials Anisotropic shader: creates surfaces with elliptical, "anisotropic" highlights. These highlights are good for modeling hair, glass, or brushed metal. Anisotropy measures the difference between sizes of the highlight as seen from two perpendicular directions. When anisotropy is 0, there is no difference at all. The highlight is circular, as in Blinn or Phong shading. When anisotropy is 100, the difference is at its maximum. In one direction the highlight is very sharp; in the other direction it is controlled solely by Glossiness.
  • 57. Shaders and Materials Blinn shader: Blinn shading is a subtle variation on Phong shading. The most noticeable difference is that highlights appear rounder. With Blinn shading, you can obtain highlights produced by light glancing off the surface at low angles. Phong shader: Phong shading smoothen the edges between faces and renders highlights realistically for shiny, regular surfaces. This shader interpolates intensities across a face based on the averaged face normals of adjacent faces. It calculates the normal for every pixel of the face.
  • 58. Shaders and Materials  Other shaders like metal, Oren-Nayar-Blinn, or Multi-layer are generally not used in gaming.  The most common used shader is Blinn because it is simple to calculate and fast to render.  There are various customized shaders created by companies compatible for their game engines Viewport shaders/RealTime Shaders  Viewport shaders are designed primarily for games and interactive media development.  Viewport Shader is a piece of code saved with the .fx extension, based exclusively on the DirectX 9 API and its high level shader language (HLSL). DirectX 9 (or higher) must be installed on your computer; otherwise, you will not be able to see any shader rendering.  You can also have OpenGL realtime shader visible on your viewport provided your system supports and have OpenGL graphic library installed on the system.  Using realtime shaders allows artists to apply in-game shading and effects to characters and environments directly within any 3d application and see on the viewport, without having to involve developers/programmers.  Your 3D graphics card must be Shader compliant, i.e. capable of supporting vertex and pixel shaders. Make sure that your video card supports pixel shader version (2.0, 1.1, etc.)
  • 59. End Of Presentation