CS 354 Introduction

CS 354 Introduction Mark Kilgard University of Texas January 17, 2012

CS 354—Computer Graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Expectations ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Grading ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Textbook ,[object Object],[object Object],[object Object],[object Object],[object Object]

Helpful Resources ,[object Object],[object Object],[object Object],OpenGL Programming Guide a.k.a. “the red book” OpenGL SuperBible OpenGL A Primer Eric Lengyel’s Mathematics for 3D Game Programming and Computer Graphics Real-Time Rendering by Eric Haines, Tomas Akenine-Moller, Eric Haines, Naty Hoffman

Computer Graphics ,[object Object],Human Perception Artistic Expression Physics of Light Geometry and Mathematics of Surfaces Computer Science VLSI Hardware Design Display & Input Technology Animation & Simulation

Roles for Computer Graphics [Pixar 2010] Story telling Product design [CATIA] Roles for Computer Graphics

Roles for Computer Graphics Training [Commercial simulators] Gaming [Skyrim]

Roles for Computer Graphics User interfaces [Android 4.0] Navigation [Audi]

Roles for Computer Graphics Printing Digital imaging & video [HP Deskjet] [Canon]

What does computer graphics study? ,[object Object],[object Object],[object Object],[object Object],[Litke et.al. 2001] [Chai & Hodgins, 2005] [Sloan et.al. 2005]

Not covered in the class ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Visual Thinking ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Reductionist Approach ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Your Modern World View: Discrete Information, Particularly Images ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Shape: Objects to Triangles ,[object Object],[object Object],More triangles makes the mesh an increasingly accurate approximation of the bunny shape

What will you learn ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What is OpenGL? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[Marathon Oil visionarium] [ES2 tablet] [MacBook]

OpenGL as an Evolving Standard EXT SGI SGIS SGIX ARB NV Others Others ,[object Object],[object Object],[object Object],ATI APPLE MESA Source: http://www.opengl.org/registry (Dec 2008)

Forces Driving Improvements in Computer Graphics Human desire for Visual Intuition and Entertainment Embarrassing Parallelism of Graphics Increasing Semiconductor Density Particularly the hardware-amenable, latency tolerant nature of rasterization Particularly interactive video games Computer Graphics Moore’s Law

Key Trend in OpenGL Evolution Fixed-function Programmable Simple Configurability Complex Configurability Shaders! High-level languages

Many Perspectives on OpenGL ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Programmer’s View: OpenGL API Example ,[object Object],glShadeModel ( GL_SMOOTH ); // smooth color interpolation glEnable ( GL_DEPTH_TEST ); // enable hidden surface removal glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glBegin (GL_TRIANGLES); { // every 3 vertexes makes a triangle glColor4ub (255, 0, 0, 255); // RGBA=(1,0,0,100%) glVertex3f (-0.8, 0.8, 0.3); // XYZ=(-8/10,8/10,3/10) glColor4ub (0, 255, 0, 255); // RGBA=(0,1,0,100%) glVertex3f ( 0.8, 0.8, -0.2); // XYZ=(8/10,8/10,-2/10) glColor4ub (0, 0, 255, 255); // RGBA=(0,0,1,100%) glVertex3f ( 0.0, -0.8, -0.2); // XYZ=(0,-8/10,-2/10) } glEnd (); Pro Tip: use curly braces to “bracket” nested OpenGL usage; no semantic meaning, just highlights grouping

Initial Logical Coordinate System ,[object Object],(-0.8, 0.8) (-0.8, 0.8) (0, -0.8) origin at (0,0)

Visualizing Normalized Device Coordinates ,[object Object],[object Object],Wire frame cube shows boundaries of NDC space From NDC views, you can see triangle isn’t “ flat” in the Z direction Two vertices have Z of -0.2—third has Z of 0.3

Programmer’s View: GLUT API Example ,[object Object],#include <GL/glut.h> // includes necessary OpenGL headers void display() { // << insert code on prior slide here >> glutSwapBuffers (); } void main(int argc, char **argv) { // request double-buffered color window with depth buffer glutInitDisplayMode ( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH ); glutInit (&argc, argv); glutCreateWindow (“simple triangle”); glutDisplayFunc (display); // function to render window glutMainLoop (); } FYI: GLUT = OpenGL Utility Toolkit

Reductionism for Rendering Objects and Scenes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Programmer’s View: Also Programming Shaders inside GPU ,[object Object],[object Object],[object Object],Geometry Program 3D Application or Game OpenGL API GPU Front End Vertex Assembly Vertex Shader Clipping, Setup, and Rasterization Fragment Shader Texture Fetch Raster Operations Framebuffer Access Memory Interface CPU – GPU Boundary OpenGL 3.3 Attribute Fetch Primitive Assembly Parameter Buffer Read programmable fixed-function Legend

Example Simple GLSL Shaders ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],void main(void) { gl_FrontColor = gl_Color ; gl_Position = ftransform (); } void main(void) { gl_FragColor = gl_Color ; } Shaders are way more interesting than these minimal examples

Building Up Shaders   ) + ( ( ) = Diffuse Gloss Specular Decal Result

OpenGL’s Design Philosophy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Later had OpenGL ES subset for embedded devices

OpenGL state machine Complicated from inception

Higher-level View of OpenGL ,[object Object]

Evolved OpenGL Data Flow vertex shading rasterization & fragment shading texture raster operations framebuffer pixel unpack pixel pack vertex puller client memory pixel transfer glReadPixels / glCopyPixels / glCopyTex{Sub}Image glDrawPixels glBitmap glCopyPixels glTex{Sub}Image glCopyTex{Sub}Image glDrawElements glDrawArrays selection / feedback / transform feedback glVertex* glColor* glTexCoord* etc. blending depth testing stencil testing accumulation storage operations

Buffer-centric Evolution ,[object Object],[object Object],Vertex Array Buffer Object (VaBO) Transform Feedback Buffer (XBO) Parameter Buffer Object (PaBO) Pixel Unpack Buffer (PuBO) Pixel Pack Buffer (PpBO) Uniform Buffer Object (UBO) Texture Buffer Object (TexBO) Vertex Puller Vertex Shading Geometry Shading Fragment Shading Texturing Array Element Buffer Object (VeBO) Pixel Pipeline vertex data texel data pixel data parameter data glBegin, glDrawElements, etc. glDrawPixels, glTexImage2D, etc. glReadPixels, etc. Framebuffer

Extensibility ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Software and Hardware Architectures Incorporating 3D Pipelines ,[object Object],[object Object],framebuffer updates vertex processing rasterization shading X server Graphics Kernel driver GPU Hardware OpenGL driver Application OpenGL library GLUT X client libraries Operating system kernel (Linux)

Hardware Platforms depending on the OpenGL Architecture ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Conventional PC OpenGL Products Unconventional non-PC OpenGL platforms

Student’s View of OpenGL ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Next Lecture ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

CS 354 Introduction

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CS 354 Introduction