GAM531DPS931 – Week 12Textures and Samplers

Actor Composition

Actor

Mesh

Vertex Buffer

Index Buffer

Vertex Format

Material

Shaders

Uniform Buffers

Blend States

Textures

Samplers

What is a Texture?

Red | Green | Blue | Alpha

265 x 265 pixels

26 x 26 pixels 2 x 2 pixels

SF_4X4BYTE_FLOAT

Red | Green | Blue

SF_4X1BYTE_UINT SF_3X4BYTE_FLOAT SF_3X1BYTE_UINT

How Do We Make Use of Textures?

[ 0, 10, 0 ]

[ 7, -7, 0 ][ -7, -7, 0 ]

How Does The Texture Map to The Object?

Class Vertex {

};Vector<float,2> uv;Vector<> pos; [ 0, 10,

0 ]

[ 7, -7, 0 ][ -7, -7, 0 ]

[ 0, 0 ]

[ 1, 0 ]

[ 0, 1 ]

[ 1, 1 ]

[ 0.5, 0 ]

[ 0, 1 ]

[ 1, 1 ]

UVW Mapping

Rasterization And Interpolation?

[ 0, 0 ]

[ 1, 0 ]

[ 0, 1 ]

[ 1, 1 ]

[ 0, 10, 0 ]

[ 7, -7, 0 ][ -7, -7, 0 ]

[ 0.5, 0 ]

[ 0, 1 ]

[ 1, 1 ]

[ 0, 1.5, 0 ][ 0.5, 0.5 ]

[ -3 , -2, 0 ][ 0.28, 0.29 ]

Texel

What Types of Textures Are There?

1D Textures

Width (U)

2D Textures

Width (U)

Height (V)

3D Textures

Width (U)

Height (V)

Depth (W)

Where are Textures Defined?

Image Files Custom Textures

auto a = newTex2D(“custom”);

a->initCustom(2, 2, SF_4X4BYTE_FLOAT);

float t[] = {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f};

a->fill((byte*)t, sizeof(t));

Render Targets

Programming Textures to Load From File

int w, h, c; unsigned char* data = SOIL_load_image(filename, &w, &h, &c, SOIL_LOAD_RGB);glGenTextures(1, &textureID); dim = GL_TEXTURE_2D;glBindTexture(GL_TEXTURE_2D, textureID);switch(c) { case 1: iFormat = GL_LUMINANCE; format = GL_RGB; break; case 2: iFormat = GL_LUMINANCE_ALPHA; format = GL_RGBA; break; case 3: iFormat = GL_RGB; format = GL_RGB; break; case 4: iFormat = GL_RGBA; format = GL_RGBA; break; }type = GL_UNSIGNED_BYTE; GLint maxTextureSize;glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);glTexStorage2D(GL_TEXTURE_2D, intLog2(min(w,h)), iFormat, w, h);glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, w, h, format, type, data);glGenerateMipmap(GL_TEXTURE_2D); SOIL_free_image_data(data);

D3DX11CreateShaderResourceViewFromFile(dev, filename, 0, 0, &texture, 0);//zeroes are load options, pump thread, hresult

Programming Custom Textures

glGenTextures(1, &textureID);dim = GL_TEXTURE_1D;glBindTexture(GL_TEXTURE_1D, textureID);//Translate formatiFormat = _glTranslateFormat(fmt, format, type);glTexStorage1D(GL_TEXTURE_1D, 1, iFormat, size);

//This is only for 1D Textures

D3D11_TEXTURE1D_DESC desc;ZeroMemory(&desc, sizeof(D3D11_TEXTURE1D_DESC));

desc.ArraySize = //number of arrays (1 usually)desc.BindFlags = //how the texture will be useddesc.CPUAccessFlags = //how the CPU can accessdesc.Format = //color format (use translation)desc.MipLevels = //number of mip maps (more later)desc.MiscFlags = //other flags (set to 0)desc.Usage = //dynamic for custom meshesdesc.Width = //the width in texels

Dev->CreateTexture1D(&desc, 0, &tex1d);Dev->CreateShaderResourceView(tex1d, 0, &texture);

//This is only for 1D Textures

Binding Textures to Shaders

glActiveTexture(GL_TEXTURE0 + slot);glBindTexture(dim, textureID);

//OpenGL does not require separate binds for each //shader type, dim is the type of texture to bind

//bind to fragment shadercon->PSSetShaderResources(slot, 1, &texture);//bind to vertex shadercon->VSSetShaderResources(slot, 1, &texture);

//slot is the memory slot in the shader the //texture will be associated with, 1 is the number//of textures to bind

Filling Custom Textures

glBindTexture(GL_TEXTURE_1D, textureID);

glTexSubImage1D(GL_TEXTURE_1D, 0, 0, size / texelSize, format, type, data);

D3D11_MAPPED_SUBRESOURCE sub;

con->Map(tex1d, 0, D3D11_MAP_WRITE_DISCARD, 0, &sub);

memcpy(sub.pData, data, size);

con->Unmap(tex1d, 0);

Texture Samplers

Texture Sampler defines how texels will be sampled from a texture to be applied to geometry in the world

Minification and Magnification

20 x 20 texelsTexture

[ 0, 0 ]

[ 1, 0 ]

[ 0, 1 ]

[ 1, 1 ]

[ 0, 0 ]

[ 1, 0 ]

[ 0, 1 ]

[ 1, 1 ]

10 x 10 pixelsGeometry

(clip space)

Interpolated UVs

[0,0] [0.1,0][0.2,0] [0.3,0][0.4,0] [0.5,0][0.6,0] [0.7,0][0.8,0] [0.9,0]

Texel Coords[0,0] [0.05,0]

[0.1,0] [0.15,0][0.2,0] [0.25,0][0.3,0] [0.35,0][0.4,0] [0.45,0][0.5,0] [0.55,0][0.6,0] [0.65,0][0.7,0] [0.75,0][0.8,0] [0.85,0][0.9,0] [0.95,0]

Point Sampling

Texture Filtering

Point Sampling(Sample Once)

UV = [0.2,0]

[0, 0, 0]

Linear Sampling(Sample Two Closest, Average)

UV = [0.2,0]

[26,26,26]

[ 0, 0, 0 ] * 1.0

0.2-(1/3)/(1/3)=0.1

[ 0, 0, 0 ] * 0.9 +

[255,255,255] * 0.1

Bilinear Sampling

(Sample Four Closest, Average)

UV = [0.2,0]

[26,26,26]

~Equation above, but in 4 directions

Texture Address Modes

Wrap

UV[3.4,2.1] = Texel[0.4,0.1]

Mirror

UV[3.4,2.1] = Texel[0.6,0.1]

Clamp

UV[3.4,2.1] = Texel[1.0,1.0]

Border

UV[3.4,2.1] != Texel[*,*]

Texture Samplers Revisited

Mipmaps

512 x 512256 x 256128 x 128 64 x 64 32 x 32 16 x 16 8 x 8 4 x 4 2 x 2 1 x 1

1024 x 1024Geometry

280 x 280Geometry

80 x 80Geometry

Texture Filtering With Mipmaps

Point Sampling(Sample Once)

Linear Sampling(Sample Two Closest, Average)

Bilinear Sampling

(Sample Four Closest, Average)

Trilinear Sampling

(Sample Four Closest On Two Closest Mipmaps,

Average)

Increases granularity of the scene,

removes sudden changes in

texture quality

Anisotropic Filtering

512 x 512512 x 256512 x 128512 x 64512 x 32512 x 16512 x 8512 x 4512 x 2512 x 1

256 x 512256 x 256256 x 128256 x 64256 x 32256 x 16256 x 8256 x 4256 x 2256 x 1

128 x 512128 x 256128 x 128128 x 64128 x 32128 x 16128 x 8128 x 4128 x 2128 x 1

…

2X Anisotropic Filtering

Anisotropic Comparison

Programming Texture SamplersglGenSamplers(1, &samplerID);glSamplerParameteri(samplerID, GL_TEXTURE_WRAP_S, um);glSamplerParameteri(samplerID, GL_TEXTURE_WRAP_T, vm);glSamplerParameteri(samplerID, GL_TEXTURE_WRAP_R, wm);glSamplerParameterf(samplerID, GL_TEXTURE_MAX_LOD, xl);glSamplerParameterf(samplerID, GL_TEXTURE_MIN_LOD, nl);glSamplerParameteri(samplerID,GL_TEXTURE_MAG_FILTER,g);glSamplerParameteri(samplerID,GL_TEXTURE_MIN_FILTER,n);glSamplerParameterf(samplerID, GL_TEXTURE_LOD_BIAS,lb);glSamplerParameteri(samplerID, GL_TEXTURE_COMPARE_FUNC, cmf);glSamplerParameterfv(samplerID, GL_TEXTURE_BORDER_COLOR, bc.data);if(GLEW_EXT_texture_filter_anisotropic) { GLfloat mA; glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &mA); if (ma > maxAnisotropy) ma = (uint32)maxAnisotropy; glSamplerParameterf(samplerID, GL_TEXTURE_MAX_ANISOTROPY_EXT, (GLfloat)ma);}

D3D11_SAMPLER_DESC sd;

sd.Filter = //Texture Filter for min/mag/mipsd.AddressU = //Address mode for the U coordsd.AddressV = //Address mode for the V coordsd.AddressW = //Address mode for the W coordsd.MipLODBias = //Mip’s Level of detail biassd.MaxAnisotropy = //Max level of anisotropymemcpy(sd.BorderColor, bc.data, sizeof(float)*4);//Copy in the color value for the bordersd.MinLOD = //Minimum Level of Detailsd.MaxLOD = //Maximum Level of Detailsd.ComparisonFunc = //Compares sample data

dev->CreateSamplerState(&sd, &sampler);

Binding Textures to Shaders

glActiveTexture(GL_TEXTURE0 + slot);glBindSampler(slot, samplerID);

//OpenGL does not require separate binds for each //shader type

//bind to fragment shadercon->VSSetSamplers(slot, 1, &sampler);//bind to vertex shadercon->VSSetSamplers(slot, 1, & sampler);

//slot is the memory slot in the shader the //texture will be associated with, 1 is the number//of samplers to bind

To Do• Finish up work on engine enhancement

• Read this week’s lab

• Read this week’s notes

• Re-implement OpenGL Texture and Sampler functions