Texture Mapping

1
Texture Mapping
2
Introduction

• What is Texture Mapping?
• Types of Texture Mapping
• 1D, 2D and 3D
• SDL and OpenGL

3
Getting Your Feet Wet

• Five Steps in Getting Texture Mapping to Work
• 1. Load the Bitmap
• 2. Generate the Texture Handle
• 3. Bind and Configure
• 4. Build Texture in OpenGL
• 5. Bind and Use

4
A Little More Detail

• 1. Load Bitmap
• 2. Generate a Texture Handle
• glGenTextures(1, temptex)
• 3. Bind and Configure
• glBindTexture (GL_TEXTURE_2D, nNewTextureID)
• glTexParameteri (GL_TEXTURE_2D,
  GL_TEXTURE_MAG_FILTER, GL_LINEAR)
• glTexParameteri (GL_TEXTURE_2D,
  GL_TEXTURE_MIN_FILTER, GL_LINEAR)
• glTexParameteri (GL_TEXTURE_2D,
  GL_TEXTURE_WRAP_S, GL_REPEAT)
• glTexParameteri (GL_TEXTURE_2D,
  GL_TEXTURE_WRAP_T, GL_REPEAT)
• 4. Build the Texture in OpenGL
• gluBuild2DMipmaps (GL_TEXTURE_2D, nBPP, nWidth,
  nHeight,
• (nBPP 3 ? GL_RGB GL_RGBA),GL_UNSIGNED_BYTE
  ,
• pData)

5
In Depth Discussion

• The Bitmap File Format
• File Header
• Size and Type of File
• Info Header
• Image dimensions
• Bits per Pixel (BPP)
• Image Data(unsigned char)
• What can be used as a Texture?

6
In Depth Discussion

• Texture Handle Generation
• glGenTextures(1, temptex)
• GL_TEXTURE_1D and GL_TEXTURE_3D
• Texture Binding
• glBindTexture (GL_TEXTURE_2D, TextureID)
• Environment Settings
• glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,
  GL_MODULATE)
• GL_DECAL and GL_BLEND

7
In Depth Discussion

• Texture Wrapping Parameters
• glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
  GL_REPEAT)
• glTexParameteri(GL_TEXTURE_2D,
  GL_TEXTURE_WRAP_T, GL_REPEAT)
• Also GL_CLAMP

8
In Depth Discussion

• Texture Resizing Filters
• glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILT
  ER, GL_NEAREST)
• GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST,
  GL_NEAREST_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_NEAREST
  , and GL_LINEAR_MIPMAP_LINEAR
• glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILT
  ER, GL_NEAREST)
• GL_LINEAR

9
In Depth Discussion

• What are Mipmaps?
• Building the Texture
• gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, width,
  height, GL_RGB, GL_UNSIGNED_BYTE, data)
• Using the Texture
• glTexCoord2f(0.0, 1.0) glVertex3i(-1, 1, 1)

10
Texture and Lighting

• Four Steps for Lighting
• Calculate Normals
• Position Light
• Choose Shading Model
• Set Material
• Setting Materials
• glMaterialfv(GL_FRONT, GL_AMBIENT, matAmbient)
• glMaterialfv(GL_FRONT, GL_DIFFUSE, matDiffuse)

11
Texture Transparency

• The Blending Function
• glEnable(GL_BLEND)
• glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
  
• glColor4f(1.0f, 1.0f, 1.0f, 0.5)
• Depth Testing Issues

12
Playing with Texture Coordinates

• Easy as Pie
• Take your original Texture coordinates and move
  them around
• Use Texture Coordinates to only show part of the
  image
• Textured Fonts

13
Multi-Pass Multi-Texturing

• What is Multi-Texturing
• Why not Single Pass Multi-Texturing
• How to do Multi-Pass Multi-Texturing
• 1. Draw your object with base texture
• 2. Draw your object again with blended texture
• 3. Repeat step 2 till satisfied

14
Advanced Topics

• Other uses of Texture Mapping
• Imposters
• Lightmapping
• Shadowmapping
• Environment Mapping
• Projective Texturing
• Procedural Texture Generation