Texture Mapping
Introduction • What is Texture Mapping? • Types of Texture Mapping • 1D, 2D and 3D • SDL and OpenGL
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
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);
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?
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
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
In Depth Discussion • Texture Resizing Filters • glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 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_FILTER, GL_NEAREST) • GL_LINEAR
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)
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)
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
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
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
Advanced Topics • Other uses of Texture Mapping • Imposters • Lightmapping • Shadowmapping • Environment Mapping • Projective Texturing • Procedural Texture Generation
