1. GAM531 DPS931 – Week 12
Textures and Samplers

2. Actor Composition Actor Mesh Material Shaders Textures Vertex Buffer
Index Buffer
Vertex Format
Material
Shaders
Uniform Buffers
Blend States
Textures
Samplers

3. What is a Texture? 2 x 2 pixels 265 x 265 pixels 26 x 26 pixels
Red | Green | Blue | Alpha
Red | Green | Blue
SF_4X4BYTE_FLOAT
SF_4X1BYTE_UINT
SF_3X4BYTE_FLOAT
SF_3X1BYTE_UINT

4. How Do We Make Use of Textures?
[ 0, 10, 0 ]
[ -7, -7, 0 ]
[ 7, -7, 0 ]

5. How Does The Texture Map to The Object?
UVW Mapping
Class Vertex {
[ 0, 10, 0 ]
Vector<> pos;
[ 0.5, 0 ]
Vector<float,2> uv;
[ 0, 0 ]
[ 1, 0 ] };
[ -7, -7, 0 ]
[ 7, -7, 0 ]
[ 0, 1 ]
[ 1, 1 ]
[ 0, 1 ]
[ 1, 1 ]

6. Rasterization And Interpolation?
[ 0, 10, 0 ]
[ 0.5, 0 ]
[ 0, 0 ]
[ 1, 0 ]
[ 0, 1.5, 0 ]
[ 0.5, 0.5 ]
[ -3 , -2, 0 ]
[ 0.28, 0.29 ]
[ 0, 1 ]
[ 1, 1 ]
[ -7, -7, 0 ]
[ 7, -7, 0 ]
Texel
[ 0, 1 ]
[ 1, 1 ]

7. What Types of Textures Are There?
3D Textures
1D Textures
2D Textures
Width (U)
Height
(V)
Height
(V)
Width (U)
Depth (W)
Width (U)

8. Where are Textures Defined?
Image Files
Custom Textures
Render Targets
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));

9. 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;
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

10. Programming Custom 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 used
desc.CPUAccessFlags = //how the CPU can access
desc.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 meshes
desc.Width = //the width in texels
Dev->CreateTexture1D(&desc, 0, &tex1d);
Dev->CreateShaderResourceView(tex1d, 0, &texture);
//This is only for 1D Textures
glGenTextures(1, &textureID);
dim = GL_TEXTURE_1D;
glBindTexture(GL_TEXTURE_1D, textureID);
//Translate format
iFormat = _glTranslateFormat(fmt, format, type);
glTexStorage1D(GL_TEXTURE_1D, 1, iFormat, size);
//This is only for 1D Textures

11. Binding Textures to Shaders
//bind to fragment shader
con->PSSetShaderResources(slot, 1, &texture);
//bind to vertex shader
con->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
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

12. Filling Custom Textures
D3D11_MAPPED_SUBRESOURCE sub;
con->Map(tex1d, 0, D3D11_MAP_WRITE_DISCARD, 0, &sub);
memcpy(sub.pData, data, size);
con->Unmap(tex1d, 0);
glBindTexture(GL_TEXTURE_1D, textureID);
glTexSubImage1D(GL_TEXTURE_1D, 0, 0, size / texelSize, format, type, data);

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

14. Minification and Magnification
[ 0, 0 ]
[ 1, 0 ]
[ 0, 0 ]
[ 1, 0 ]
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]
[ 0, 1 ]
[ 1, 1 ]
[ 0, 1 ]
[ 1, 1 ]
20 x 20 texels Texture
10 x 10 pixels Geometry
(clip space)
Point Sampling

15. Texture Filtering [0, 0, 0] Point Sampling (Sample Once) UV = [0.2,0]
[ 0, 0, 0 ] * 1.0
[26,26,26]
0.2-(1/3)/(1/3)=0.1
[ 0, 0, 0 ] * [255,255,255] * 0.1
Linear Sampling
(Sample Two Closest, Average)
UV = [0.2,0]
[26,26,26]
~Equation above, but in 4 directions
Bilinear Sampling
(Sample Four Closest, Average)
UV = [0.2,0]

16. Texture Address Modes Wrap Mirror Clamp Border
UV[3.4,2.1] = Texel[0.4,0.1]
UV[3.4,2.1] = Texel[1.0,1.0]
UV[3.4,2.1] = Texel[0.6,0.1]
UV[3.4,2.1] != Texel[*,*]

17. Texture Samplers Revisited

18. Mipmaps
512 x 512
256 x 256
128 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 1024
Geometry
280 x 280
Geometry
80 x 80
Geometry

19. Texture Filtering With Mipmaps
Trilinear Sampling
(Sample Four Closest On Two Closest Mipmaps, Average)
Point Sampling
(Sample Once)
Linear Sampling
(Sample Two Closest, Average)
Increases granularity of the scene, removes sudden changes in texture quality
Bilinear Sampling
(Sample Four Closest, Average)

20. Anisotropic Filtering
512 x 512
512 x 256
512 x 128
512 x 64
512 x 32
512 x 16
512 x 8
512 x 4
512 x 2
512 x 1
256 x 512
256 x 256
256 x 128
256 x 64
256 x 32
256 x 16
256 x 8
256 x 4
256 x 2
256 x 1
128 x 512
128 x 256
128 x 128
128 x 64
128 x 32
128 x 16
128 x 8
128 x 4
128 x 2
128 x 1 …
2X Anisotropic Filtering

21. Anisotropic Comparison

22. Programming Texture Samplers
glGenSamplers(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/mip
sd.AddressU = //Address mode for the U coord
sd.AddressV = //Address mode for the V coord
sd.AddressW = //Address mode for the W coord
sd.MipLODBias = //Mip’s Level of detail bias
sd.MaxAnisotropy = //Max level of anisotropy
memcpy(sd.BorderColor, bc.data, sizeof(float)*4);
//Copy in the color value for the border
sd.MinLOD = //Minimum Level of Detail
sd.MaxLOD = //Maximum Level of Detail
sd.ComparisonFunc = //Compares sample data
dev->CreateSamplerState(&sd, &sampler);

23. Binding Textures to Shaders
//bind to fragment shader
con->VSSetSamplers(slot, 1, &sampler);
//bind to vertex shader
con->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
glActiveTexture(GL_TEXTURE0 + slot);
glBindSampler(slot, samplerID);
//OpenGL does not require separate binds for each
//shader type

24. 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