adrien.io opengl tutorials codex

8/9/2019 adrien.io OpenGL Tutorials Codex

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http://adrien.ioOpenGL Tutorials

Codex
http://adrien.io/


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Buffer Object

Memory managed by OpenGL

GL_ARRAY_BUFFER,GL_ELEMENT_ARRAY_BUFFER, ..

glGenBuffers, glBindBuffer, glBufferData


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Vertex Array Object

Specify where data is located and layout

GL_ARRAY_BUFFER,GL_ELEMENT_ARRAY_BUFFER, ..

glGenVertexArrays, glBindVertexArray,glVertexAttribPointer, glEnableVertexAttribArray


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Framebuffer Object Specify how draw buffers are stored

glGenFramebuffersglBindFramebuffer Framebuffer Object 0is created automatically

Attach Renderbuffer Objects : glFramebufferTextu

Attach Textures : glFramebufferTexture2D Attach to Draw BuffersGL_COLOR_ATTACHMEN Special Attachments Depthand Stencil

Clear buffers before use : glClear


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Programmable stages

Vertex Tessellation Control Tessellation Evaluation Geometry Fragment

Compute


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Vertex Shading For each vertex issued by a drawing command a v

shader is called

gl_VertexIdgl_InstanceID

Output vertex positions in screen space

Mandatory


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Tessellation Shading

Two stages : Control and Evaluation

Patches instead of points/lines/triangles

Optional stage


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Geometry Shading

Process and emit individual geometry primitives

Optional Stage

gl_PrimitiveIDIn


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Fragment Shading

Compute fragment color and depth

Texture sampling

Mandatory Stage

gl_FragCoord


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Texture Units, Samplers, and Tex Only one texture can be bound for each Texture Un

glActiveTextureselects the current Texture Unit

glBindTexturebinds the texture to the current Text

Unit

A sampler uniform is associated to a Texture Unit

Shaders read textures through a sampler.


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BAC = acos(A

AB

C ABAC = cos

AB = AB||AB||

AB = B-A


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Blinn-Phong Shading

floatndotl = clamp(dot(n, l), 0.0, 1.0);

vec3h = normalize(l-v);

floatndoth = clamp(dot(n, h), 0.0,1.0);

vec3specularColor = specularColor *pow(ndoth, specularPower);

vec3color = specularColor +diffuseColor * ndotl;


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Point Light

n

lp

p

ep

v l

l= lp-p


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Directional Light

n

p

ep

v l

l= -ld

ld


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Spot Light

n

lp

p

ep

v l

l= lp-p

ld

langle

-lld> cos(la


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Geometry Spaces

World Space : Useful for transformations and lighting

Object Space : useful for object transformations

Camera Space : Useful for lighting

Light Space : Useful for shadow mapping


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Forward Shading

Rasterization Uniforms


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Deferred Shading

Rasterization

G-Buff

Normals Materia

+ +


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Shadow Mapping

lp

p1

ep

langle

p2

dblocker

dlight

shadow = dblocker < dlight + bias


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Post-FX pipeline

T0

glFramebufferTexture2DT0

glClear

Render


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Post-FX pipeline

T0 T1

T0glFramebufferT

glClear

glBindTexture T

Render


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Post-FX pipeline

T0 T1 T0

T1T0glFrame

glClear

glBindTe

Render

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