DI-Guy Graphics API, diguyOglGraphicsTexture

diguyOglGraphicsTexture.cpp

DI-Guy API Version 12.5.1

This file was automatically generated from diguyOglGraphicsTexture.cpp. Do not edit this file directly; the changes will be lost.

Textures modify the visible appearance of meshes. They work in concert with materials to determine the final appearance of visible geometry.

The class diguyOglGraphicsTexture is an example of a diguyGraphicsTexture subclass for an immediate mode renderer using the DI-Guy Loader. The example subclass shows how to use the accessors of the diguyGraphicsTexture class and which virtual functions should be overridden for an immediate mode renderer such as OpenGL.

#include "diguyOglGraphicsTexture.h" #include <libbdilog.h> #include <stdlib.h> #include <stdio.h> #include <assert.h>

Initialize data members of the class to a known state.

Most base class data will not be fully initialized until during the Build Stage, so most base class accessors should not be called here.

diguyOglGraphicsTexture::diguyOglGraphicsTexture(void* internal_data)     :     diguyGraphicsTexture(internal_data),     m_texture_object(0) {     /*      * Nothing else to do after calling base class constructor and      * initializing data members.      */ }

Build Stage

Description:

Override of diguyGraphicsTexture::build().

The build() function should create renderer objects that will set the proper texture state in bind() calls made during the Draw Stage.

This implementation creates an OpenGL texture object for setting texture properties of meshes.

void diguyOglGraphicsTexture::build() {     const char* fname = get_filename();     unsigned char* texture_map_data = get_texture_map_data();     /*      * If there is texture data, create a mip-mapped texture object.      */     if (texture_map_data)     {         int width = get_width();         int height = get_height();         int num_components = get_num_components();         int pixel_format_as_int = get_gl_format();         if (pixel_format_as_int == -1)         {             bdi_log_printf(BDI_LOG_WARN, "WARNING: Failed to obtain legal "                 "pixel format for texture '%s'.\n",                 get_name());             goto MAKE_NULL_TEXTURE;         }         GLenum pixel_format = (GLenum) pixel_format_as_int;         /*          * Choose reasonable mag and min filters.          */         GLenum texture_mag_filter = GL_LINEAR;         GLenum texture_min_filter = GL_LINEAR_MIPMAP_LINEAR;         glGenTextures(1, &m_texture_object);         glBindTexture(GL_TEXTURE_2D, m_texture_object);         glPixelStorei(GL_UNPACK_ALIGNMENT, 4);         if (get_clamp_s())             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);         else             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);         if (get_clamp_t())             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);         else             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, texture_mag_filter);         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, texture_min_filter);         glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);         /*          * Get the texture data into OpenGL. The calls we use depend          * on whether the texture data is compressed or not.          */         diguyGraphicsTextureCompressionType compression_type = get_texture_compression_type();         //printf("%s %s\n", get_filename(), get_gl_format_as_string());         if (compression_type == DIGUY_GRAPHICS_TEXTURE_COMPRESSION_TYPE_NONE)         {             /*              * Currently uncompressed textures are assumed to not have              * included mipmaps. This doesn't take into account .dds              * files that aren't compressed, which DI-Guy doesn't yet              * support.              *              * If we've set the min filter to one of the "MIPMAP" options              * (e.g., GL_LINEAR_MIPMAP_LINEAR) we should have OpenGL create              * mipmaps. The filters GL_NEAREST and GL_LINEAR don't require              * mipmaps.              *              * http://www.opengl.org/wiki/Common_Mistakes says never use              * gluBuild2DMipmaps.              */             //gluBuild2DMipmaps(GL_TEXTURE_2D,             // num_components,             // width,             // height,             // pixel_format,             // GL_UNSIGNED_BYTE,             // texture_map_data);             int color_format = -1;             switch (num_components)             {                 case 1: color_format = GL_LUMINANCE; break;                 case 2: color_format = GL_LUMINANCE_ALPHA; break;                 case 3: color_format = GL_RGB; break;                 case 4: color_format = GL_RGBA; break;             }             glTexImage2D(GL_TEXTURE_2D,                 0,                 pixel_format,                 width,                 height,                 0,                 color_format,                 GL_UNSIGNED_BYTE,                 texture_map_data);             if ((texture_min_filter == GL_NEAREST_MIPMAP_NEAREST) ||                 (texture_min_filter == GL_NEAREST_MIPMAP_LINEAR) ||                 (texture_min_filter == GL_LINEAR_MIPMAP_NEAREST) ||                 (texture_min_filter == GL_LINEAR_MIPMAP_LINEAR))             {                 glGenerateMipmap(GL_TEXTURE_2D);             }         }         else         {             /*              * Compressed textures may already include mipmaps. If this              * is the case, we need to manually tell OpenGL the mipmap              * offsets.              */             int num_included_mipmaps = get_num_included_mipmaps();             /*              * There's always at least 1 included mipmap: the base image.              */             if (num_included_mipmaps == 0)                 num_included_mipmaps = 1;             /*              * Get mipmap offsets.              *              * "Mipmap 0" is really the base-level image. Each successive              * mipmap should decrease in width and height by a factor of 2.              */             int mipmap_width = width;             int mipmap_height = height;             assert(glCompressedTexImage2D);             int k;             for (k=0; k<num_included_mipmaps; k++)             {                 if (mipmap_width == 0) mipmap_width = 1;                 if (mipmap_height == 0) mipmap_height = 1;                 glCompressedTexImage2D(GL_TEXTURE_2D,                     k,                     pixel_format,                     mipmap_width,                     mipmap_height,                     0,                     get_mipmap_data_size(k),                     texture_map_data + get_mipmap_data_offset(k));                 mipmap_width >>= 1;                 mipmap_height >>= 1;             }             /*              * If there are missing mipmaps, the following keeps GL working              * right. Otherwise the mipmap levels that are missing would              * show up as white.              */             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, num_included_mipmaps - 1);         }     }     /*      * Else create a "null" texture object.      */     else     { MAKE_NULL_TEXTURE:      glGenTextures(1, &m_texture_object);      glBindTexture(GL_TEXTURE_2D, m_texture_object);      unsigned char buf[] = {255,255,255,255};      glTexImage2D(GL_TEXTURE_2D, 0, 4, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, buf);      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);      glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);     }     glBindTexture(GL_TEXTURE_2D, 0);     /*      * Free memory allocated by the loader. Now that the texture data is      * in an OpenGL texture object, the raw data loaded from the texture      * file can be freed.      */     free_loader_memory(); }

Unbuild Stage

Description:

Override of diguyGraphicsTexture::unbuild().

The unbuild() function should destroy the objects created in the build() function.

This implementation deletes the OpenGL texture object created in build().

void diguyOglGraphicsTexture::unbuild() {     if (m_texture_object != 0)         glDeleteTextures(1, &m_texture_object); }

Draw Stage

Description:

Override of virtual function of diguyGraphicsTexture::bind_now(), called during Draw Stage.

The bind_now() function should do whatever is necessary to change the current state of the renderer to use this texture.

The texture object created in build() is bound, changing OpenGL texture settings.

void diguyOglGraphicsTexture::bind_now(diguyTextureMapType texture_type) {     if (diguyOglGraphicsTexture::get_last_bound_texture(texture_type) == this)         return;     if (m_texture_object == 0)     {         return;     }     glActiveTexture(GL_TEXTURE0 + texture_type);     glBindTexture(GL_TEXTURE_2D, m_texture_object); }

Create and return an object of a subclass of diguyGraphicsTexture. This function will be called whenever DI-Guy requires a texture object.

diguyGraphicsTexture* diguyOglGraphicsTexture_create_func(void* internal_data) {     return new diguyOglGraphicsTexture(internal_data); }