Mohan Sridharan Based on slides created by Edward Angel GLSL I 1 CS4395: Computer Graphics.

Slides:



Advertisements
Similar presentations
GLSL Basics Discussion Lecture for CS 418 Spring 2015 TA: Zhicheng Yan, Sushma S Kini, Mary Pietrowicz.
Advertisements

Introduction to GLSL Patrick Cozzi University of Pennsylvania CIS Fall 2014.
Informationsteknologi Wednesday, December 12, 2007Computer Graphics - Class 171 Today’s class OpenGL Shading Language.
MAT 594CM S10Fundamentals of Spatial ComputingAngus Forbes Week 5 : GLSL Shaders Topics: Shader syntax, passing textures into shaders, per-pixel lighting,
GLSL II Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New.
Announcments Sign up for crits!. Reading for Next Week FvD – local lighting models GL 5 – lighting GL 9 (skim) – texture mapping.
GLSL I May 28, 2007 (Adapted from Ed Angel’s lecture slides)
GLSL I Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New Mexico.
Computer Science – Game DesignUC Santa Cruz Adapted from Jim Whitehead’s slides Shaders Feb 18, 2011 Creative Commons Attribution 3.0 (Except copyrighted.
REAL-TIME VOLUME GRAPHICS Christof Rezk Salama Computer Graphics and Multimedia Group, University of Siegen, Germany Eurographics 2006 Real-Time Volume.
Programmable Pipelines. Objectives Introduce programmable pipelines ­Vertex shaders ­Fragment shaders Introduce shading languages ­Needed to describe.
An Introduction to the OpenGL Shading Language Benj Lipchak Rob Simpson Bill Licea-Kane.
CIS 565 Fall 2011 Qing Sun
OpenGL Shading Language (Advanced Computer Graphics) Ernest Tatum.
CS 480/680 Computer Graphics Shader Applications Dr. Frederick C Harris, Jr. Fall 2011.
Lecture by: Martin Deschamps CSE 4431
Shader Basics Chap. 2 of Orange Book. 2 Contents Why write shaders OpenGL programmable processors Language overview System overview.
1 Introduction to Computer Graphics with WebGL Ed Angel Professor Emeritus of Computer Science Founding Director, Arts, Research, Technology and Science.
CS662 Computer Graphics Game Technologies Jim X. Chen, Ph.D. Computer Science Department George Mason University.
OpenGL Shader Language Vertex and Fragment Shading Programs.
1 Introduction to Computer Graphics with WebGL Ed Angel Professor Emeritus of Computer Science Founding Director, Arts, Research, Technology and Science.
Shader Applications Ed Angel Professor Emeritus of Computer Science University of New Mexico 1 E. Angel and D. Shreiner: Interactive Computer Graphics.
Shaders in OpenGL Marshall Hahn. Introduction to Shaders in OpenGL In this talk, the basics of OpenGL Shading Language will be covered. This includes.
CS418 Computer Graphics John C. Hart
GLSL OpenGL Programming and Reference Guides, other sources
OpenGL Shading Language (GLSL)
CSE 381 – Advanced Game Programming GLSL. Rendering Revisited.
OpenGL Shading Language (GLSL)
Vertex Buffer Objects and Shader Attributes. For Further Reading Angel 7 th Ed: –Most parts of Chapter 2. Beginning WebGL: –Chapter 1: vertex Buffer Objects,
GLSL II.
GLSL II Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New.
Week 3 Lecture 4: Part 2: GLSL I Based on Interactive Computer Graphics (Angel) - Chapter 9.
1 E. Angel and D. Shreiner: Interactive Computer Graphics 6E © Addison-Wesley 2012 Programming with OpenGL Ed Angel Professor Emeritus of Computer Science.
Programmable Pipelines. 2 Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009 Black Box View Geometry Processor Frame Buffer Fragment Processor.
GLSL I.
Programming with OpenGL Part 5: More GLSL Isaac Gang University of Mary Hardin-Baylor E. Angel and D. Shreiner: Interactive Computer Graphics 6E © Addison-Wesley.
What are shaders? In the field of computer graphics, a shader is a computer program that runs on the graphics processing unit(GPU) and is used to do shading.
CS 4363/6353 SHADERS/GLSL. ANOTHER LOOK AT THE PIPELINE Vertex Processing Clipping/Assembly Rasterization Fragment Processing.
OpenGL Shading Language
Programming with OpenGL Part 3: Shaders Ed Angel Professor of Emeritus of Computer Science University of New Mexico 1 E. Angel and D. Shreiner: Interactive.
OpenGl Shaders Lighthouse3d.com.
GLSL I.  Fixed vs. Programmable  HW fixed function pipeline ▪ Faster ▪ Limited  New programmable hardware ▪ Many effects become possible. ▪ Global.
Advanced Texture Mapping Bump Mapping & Environment Mapping (Reflection)
GLSL II Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New.
An Introduction to the Cg Shading Language Marco Leon Brandeis University Computer Science Department.
GLSL Review Monday, Nov OpenGL pipeline Command Stream Vertex Processing Geometry processing Rasterization Fragment processing Fragment Ops/Blending.
COMP 175 | COMPUTER GRAPHICS Remco Chang1/XX13 – GLSL Lecture 13: OpenGL Shading Language (GLSL) COMP 175: Computer Graphics April 12, 2016.
Shaders, part 2 alexandri zavodny.
Introduction to Computer Graphics with WebGL
Shader.
CSE Real Time Rendering
GLSL II Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New.
Carl Johan Gribel, PhD student
Chapter 6 GPU, Shaders, and Shading Languages
Objectives Simple Shaders Programming shaders with GLSL
GLSL I Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts Director, Arts Technology Center University of New Mexico.
Introduction to Computer Graphics with WebGL
Day 05 Shader Basics.
UMBC Graphics for Games
Introduction to Computer Graphics with WebGL
Shader Basics Chap. 2 of Orange Book.
ICG 2018 Fall Homework1 Guidance
Programming with OpenGL Part 3: Shaders
Mickaël Sereno Shaders Mickaël Sereno 25/04/2019 Mickaël Sereno -
CS 480/680 Computer Graphics GLSL Overview.
Language Definitions Chap. 3 of Orange Book.
CS 480/680 Part 1: Model Loading.
Introduction to Computer Graphics with WebGL
Programmable Pipelines
CS 480/680 Fall 2011 Dr. Frederick C Harris, Jr. Computer Graphics
Presentation transcript:

Mohan Sridharan Based on slides created by Edward Angel GLSL I 1 CS4395: Computer Graphics

Objectives Shader applications: – Vertex shaders. – Fragment shaders. Programming shaders: – Cg. – GLSL. CS4395: Computer Graphics 2

Vertex Shader Applications Moving vertices: – Morphing. – Wave motion. – Fractals. Lighting: – More realistic models. – Cartoon shaders. CS4395: Computer Graphics 3

Fragment Shader Applications Per fragment lighting calculations: CS4395: Computer Graphics 4 per vertex lighting per fragment lighting

Fragment Shader Applications Texture mapping: CS4395: Computer Graphics 5 smooth shadingenvironment mapping bump mapping

Writing Shaders First programmable shaders were programmed in an assembly-like manner. OpenGL extensions for vertex and fragment shaders. Cg (C for graphics) C-like language for programming shaders: – Works with both OpenGL and DirectX. – Interface to OpenGL complex. OpenGL Shading Language (GLSL). CS4395: Computer Graphics 6

GLSL OpenGL Shading Language. Part of OpenGL 2.0. High level C-like language. New data types: matrices, vectors, samplers. OpenGL state available through built-in variables. CS4395: Computer Graphics 7

Simple Vertex Shader const vec4 red = vec4(1.0, 0.0, 0.0, 1.0); void main(void) { gl_Position = gl_ProjectionMatrix *gl_ModelViewMartrix*gl_Vertex; gl_FrontColor = red; } CS4395: Computer Graphics 8

Execution Model CS4395: Computer Graphics 9

Simple Fragment Program void main(void) { gl_FragColor = gl_Color; } CS4395: Computer Graphics 10

Execution Model CS4395: Computer Graphics 11

Data Types C types: int, float, bool. Vectors: – float vec2, vec3, vec4. – Also int (ivec) and boolean (bvec). Matrices: mat2, mat3, mat4. – Stored by columns. – Standard referencing m[row][column]. C++ style constructors: – vec3 a =vec3(1.0, 2.0, 3.0). – vec2 b = vec2(a). CS4395: Computer Graphics 12

Pointers There are no pointers in GLSL. We can use C structs which can be copied back from functions. Because matrices and vectors are basic types they can be passed into and output from GLSL functions: matrix3 func(matrix3 a) CS4395: Computer Graphics 13

Qualifiers GLSL has many of the same qualifiers ( const) as C/C++. Need others due to the nature of the execution model. Variables can change: – Once per primitive. – Once per vertex. – Once per fragment. – At any time in the application. Vertex attributes are interpolated by the rasterizer into fragment attributes. CS4395: Computer Graphics 14

Attribute Qualifier Attribute-qualified variables can change at most once per vertex: – Cannot be used in fragment shaders. Built in (OpenGL state variables): – gl_Color – gl_ModelViewMatrix User defined (in application program): – attribute float temperature – attribute vec3 velocity CS4395: Computer Graphics 15

Uniform Qualified Variables that are constant for an entire primitive. Can be changed in application outside scope of glBegin and glEnd. Cannot be changed in shader. Used to pass information to shader such as the bounding box of a primitive. CS4395: Computer Graphics 16

Varying Qualified Variables passed from vertex shader to fragment shader. Automatically interpolated by the rasterizer. Built in: – Vertex colors. – Texture coordinates. User defined: – Requires a user defined fragment shader. CS4395: Computer Graphics 17

Example: Vertex Shader const vec4 red = vec4(1.0, 0.0, 0.0, 1.0); varying vec3 color_out; void main(void) { gl_Position = gl_ModelViewProjectionMatrix*gl_Vertex; color_out = red; } CS4395: Computer Graphics 18

Required Fragment Shader varying vec3 color_out; void main(void) { gl_FragColor = color_out; } CS4395: Computer Graphics 19

Passing values Call by value-return. Variables are copied in. Returned values are copied back. Three possibilities: – In. – Out. – Inout. CS4395: Computer Graphics 20

Operators and Functions Standard C functions: – Trigonometric. – Arithmetic. – Normalize, reflect, length. Overloading of vector and matrix types: mat4 a; vec4 b, c, d; c = b*a; // a column vector stored as a 1d array d = a*b; // a row vector stored as a 1d array CS4395: Computer Graphics 21

Swizzling and Selection Can refer to array elements by element using [] or selection (.) operator with : – x, y, z, w – r, g, b, a – s, t, p, q – a[2], a.b, a.z, a.p are the same. Swizzling operator lets us manipulate components: vec4 a; a.yz = vec2(1.0, 2.0); CS4395: Computer Graphics 22