Introduction to OpenGL.ppt

Introduction to OpenGL.ppt

• 1.
  CSE 4208 Introduction toOpenGL Conducted By: Sk. Md. Masudul Ahsan and Kazi Saeed Alam
• 2.
  Objective of graphicsprogramming  To create synthetic image such a way that it is close to reality.  To create artificial animation that emulates virtual reality.  But why? We have already tools like camera to create image of natural scene and video camera for creating natural movies! 2
• 3.
  OpenGL – OpenGraphics Library  What it is ?  a software interface to graphics hardware  a graphics programming library  Dominant industry "standard" for 3D graphics  Consists of about 150 basic commands  Platform independent  What it is not ?  a windowing system (no window creation)  a UI system (no keyboard and mouse routines)  a 3D modeling system (Open Inventor, VRML, Java3D) 3
• 4.
  OpenGL Related Libraries GL – gl.h – Opengl32.lib  Provides basic commands for graphics drawing  GLU (OpenGL Utility Library) – glu.h – glu32.lib  Uses GL commands for performing compound graphics like  viewing orientation and projection specification  polygon tessellations, surface rendering etc.  GLUT (OpenGL Utility Toolkit) – glut.h – glut.lib  is a window system-independent toolkit for user interaction 4
• 5.
  OpenGL Library Organization GLU GL Generic GraphicsAPI GLUT User Interface DirectDraw WGL Xlib / Xt GLX OpenGL Application Program Frame Buffer Host OS Either will Exist in any system 5
• 6.
  Object space andworld space Object space World Space Instantiate & Modeling Transform 6
• 7.
  Eye space  Amodel can be viewed from different angles.  Viewing Transform specify following information about the viewer:  eye position  head up  Look at direction  View volume 7
• 8.
  Pipelined architecture a c b a *  *+ b c Arithmetic pipeline for c b a *  8
• 9.
  Geometric pipeline Transformer ClipperProjector Rasterizer Pixels vertices 9
• 10.
  OpenGL graphics Pipeline Graphics Primitives Object Space transform matrix Modeling Transform World Space Eye,lookat, headup Viewing Transform Eye Space Parallel or Perspectiv e volume Normalize & Clip Clipping Space material, lights, color Shading & Texture viewport location Image on Screen Viewport Transform Device Space Image Space Projection projection matrix Image in Internal Buffer Rasteri- zation Screen Space Scan conversio n 10
• 11.
  Convention of functionnaming glColor3f(...) Gl library Root Command Number of Arguments Type of Arguments 11
• 12.
  OpenGL APIs  Primitivefunctions glBegin(type); glVertex(…); glVertex(…); … glVertex(…); glEnd();  Attribute functions glColor3f(…); 12
• 13.
  OpenGL APIs  Transformationfunctions glRotate(…); glTranslate(…);  Viewing functions gluLookAt(…);  Input functions glutKeyboardFunc(…);  Control functions  Inquiry functions 13
• 14.
  Primitives  Primitives: Points,Lines & Polygons  Each object is specified by a set of Vertices • Grouped together by glBegin & glEnd glBegin(type) glVertex*( ) glVertex*( ) … glEnd( ); • type can have 10 possible values To specify attributes of last Vertex drawn: glColor*()/ glIndex*() current vertex color glNormal*() current vertex normal (lighting) glMaterial*() current material property (lighting) glTexCoord*() current texture coordinate glEdgeFlag*() edge status (surface primitives) 14
• 15.
  Primitive Types GL_POINTS V0 V1 V2 V3 V5 V4 GL_LINE_LOOP V0 V1 V2 V3 V5 V4 GL_LINES V0 V1 V2 V3 V5 V4 GL_LINE_STRIP V0 V1 V2 V3 V5 V4 GL_POLYGON V0 V1 V2 V3 V4 Polygon mustbe: •Simple •No-holes inside •Convex Simple Non-convex Complex Convex P1 P2 15
• 16.
  Primitive Types GL_TRIANGLES V0 V1 V2 V3 V4 V5 V6 V7 V8 GL_QUADS V0 V1 V2 V3 V4 V5 V6 V7 GL_TRIANGLE_STRIP V0 V1 V2 V3 V4 V5 Order ofVertex rendering GL_TRIANGLE_STRIP 012, 213, 234, 435 GL_QUAD_STRIP V0 V1 V2 V3 V4 V5 V6 V7 GL_QUAD_STRIP 0132, 2354, 4576 GL_TRIANGLE_FAN V0 V1 V2 V3 V4 V5 GL_TRIANGLE_FAN 012, 023 , 034, 04516
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  Finally  Making yourprogramming environment ready  Let’s see some projects  Your first program  Now try with some more stuffs 17