1 / 13

Texture Management

Texture Management. Michael I. Gold NVIDIA Corporation. Overview. Texture Objects Texture Internal Formats The EXT_packed_pixels extension Dynamic Texture Updates. glTexImage2D. Overview Texture image specification glTexImage2D( target, lod, components , width, height, border,

renata
Download Presentation

Texture Management

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Texture Management Michael I. Gold NVIDIA Corporation

  2. Overview • Texture Objects • Texture Internal Formats • The EXT_packed_pixels extension • Dynamic Texture Updates

  3. glTexImage2D • Overview • Texture image specification glTexImage2D( target, lod, components, width, height, border, type, format, data);

  4. Internal Formats • OpenGL 1.0 - components • 1, 2, 3, 4 • OpenGL 1.1 - internalformat • ALPHA, LUMINANCE, INTENSITY, LUMINANCE_ALPHA, RGB, RGBA • Two new single-component formats • ALPHA - alpha channel only • INTENSITY - RGBA use same value

  5. Sized Formats • Driver chooses default storage format • “ What were they thinking?” • You can give the driver a hint • Driver uses closest supported format • RGB5 vs. RGB8 • RGBA4 vs. RGB5_A1 vs. RGBA8 • see TexImage2D reference for complete list • Greater control over performance/quality tradeoffs

  6. glGetTexLevelParameter • What format did I get? • Component sizes may be queried glGetTexLevelParameteriv( GL_TEXTURE_2D, lod, GL_RED_SIZE, &redSize);

  7. EXT_packed_pixels • Faster texture downloads • Textures are often stored in 16-bit formats • OpenGL 1.1 textures must be expanded • Driver often repacks textures internally • EXT_packed_pixels allows packed data to be sent to the driver • Supported in SGI ICD kit

  8. EXT_packed_pixels (cont’d) • New data types • GL_UNSIGNED_SHORT_4_4_4_4_EXT • GL_UNSIGNED_SHORT_5_5_5_1_EXT • see extension spec for complete set • Use with corresponding internal format for best results

  9. EXT_packed_pixels (cont’d) • Example - 5551 packed data glTexImage2D(GL_TEXTURE_2D, lod, GL_RGB5_A1, w, h, 0, GL_UNSIGNED_SHORT_5_5_5_1_EXT, GL_RGBA, data);

  10. Texture Objects - Old Way • OpenGL 1.0 - Display Lists • difficult to optimize GLuint tex = glGenLists(1); glNewList(tex, GL_COMPILE); glTexImage2D(GL_TEXTURE_2D, …); glEndList(); glCallList(tex);

  11. Texture Objects - New Way • OpenGL 1.1 - Texture Objects • more elegant • higher performance GLuint tex; glGenTextures(1, &tex); glBindTexture(GL_TEXTURE_2D, tex); glTexImage2D(GL_TEXTURE_2D, …); glBindTexture(GL_TEXTURE_2D, tex);

  12. Dynamic Texture Updates • Divide static and dynamic textures • Let OpenGL cache static textures • Only update dynamic textures • Use glTexSubImage if possible • Re-use same “shape” textures if possible • Sort textures by size

  13. Dynamic Texture Updates • Don’t change one texture multiple times per frame • Ping-pong between two “dynamic” textures, alternating frames • Utilize texture matrix to avoid downloads if possible • Minimize state changes - changing textures is expensive

More Related