OpenGL ES Intro

March 20, 2018 | Author: Anonymous | Category: N/A
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What is

?

 Open Graphics Library  A cross-language, multi-platform API for rendering 2D

   

and 3D computer graphics. The API is used to interact with a Graphics Processing Unit (GPU) Achieve hardware-accelerated rendering. OpenGL was developed by Silicon Graphics Inc. For more information: http://en.wikipedia.org/wiki/OpenGL

What is

?

 An application interface to access GPU.

What can

do??

 Draw points, lines, and polygons.

OpenGL.org

Lambertian reflection

Diffuse and specular reflection from a glossy surface, e.g. polished marble.

What can

do?

 Add lighting effect in the scene. 

Ambient light: gross approximation of light, which produces constant illumination on all surface.

OpenGL.org

What can

do?

 Add lighting effect in the scene. 

Diffuse light: reflection of light from a surface that is reflected at many angles rather than at just one angle.

OpenGL.org

What can

do?

 Add lighting effect in the scene. 

Specular light: mirror-like reflection of light from a surface with a single outgoing direction.

OpenGL.org

What can

do??

 With different lighting parameters for an object, the

object have different appearances. No Ambient

Gray Ambient Blue Ambient Diffuse Only

Specular

Higher Emission Shininess

CG course in NCTU

What can

do?

 Map textures to the surface of an object.

CG course in NCTU

function pipeline  Before OpenGL 2.0 Triangles/Lines/Points

API

Primitive Processing

Vertices

Vertex Buffer Objects

Alpha Test

Transform and Lighting

Primitive Assembly

Rasterizer

Texture Environment

Colour Sum

Fog

Depth Stencil

Colour Buffer Blend

Dither

Frame Buffer

Primitive Assembly  Primitives are broken down into individual points,

lines, and triangles.  For example, triangle strip to be rendered. Then the triangle strip is converted into triangles.

Fixed function pipeline  Transformation & lighting  Model, view, projection transformation  Lighting computation  Texture Environment  Texture coordinate computation  Colour Sum  Fog  Alpha Test  For the transparent object in the scene

function pipeline  ES2.0 Programming Pipeline Triangles/Lines/Points

API

Primitive Processing

Vertices

Vertex Shader

Vertex Buffer Objects

Primitive Assembly

Rasterizer

Fragment Shader

Depth Stencil

Colour Buffer Blend

Dither

Frame Buffer

OpenGL.org

Programmable function pipeline  Vertex Shader  Handle Transformation & lighting part in fixed pipeline.  Fragment Shader  Handle the following parts in fixed pipeline    

Texture Environment Colour Sum Fog Alpha Test

Additional Information  OpenGL (Open Graphics Library)  For more information:  

http://www.opengl.org/ Book: Donald D. Hearn, M. Pauline Baker, “Computer Graphics with OpenGL”, 3/E, Prentice Hall, 2004

What is

??

 OpenGL ES ( OpenGL for Embedded System )  A subset of the OpenGL application programming interface (API)  Designed for embedded systems 

mobile phones, Personal Digital Assistant(PDAs), and video game consoles.

 Lightweight interface  Differences from OpenGL  Programmers need to compute projection matrix & transformation matrix.  No glBegin() and glEnd(). No GL_QUADS and GL_POLYGONS.  Vertex information are attributes.  For more information:

http://en.wikipedia.org/wiki/OpenGL_ES

What can

do ?

 OpenGL ES  Draw points, lines, triangles.  Render meshes with textures and lighting effects, etc.

Draw polygons

Put a light in the scene

Texturing the objects

function pipeline  In OpenGL ES 1.0/1.1  Use fixed function pipeline  In OpenGL ES 2.0  Use programmable function pipeline

Additional Information  OpenGL ES  For more information:  



http://www.khronos.org/opengles/ Android OpenGL ES lessons http://developer.android.com/training/graphics/opengl/inde x.html Learn OpenGL ES http://www.learnopengles.com/

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