Guha's Texture Example Code

• This is in "Old" OpenGL
• But I will produce some in "New" OpenGL by next Monday.
• Code
  • loadTextures.cpp
  • getbmp.cpp
  • getbmp.h
  • Makefile
• It also involves an image file
• getbmp
  • Is a routine that reads in a .bmp file format
  • Is not outside the scope of the class, but is not very interesting.
  • Just parsing data according to a given format
  • Some binary level io and file manipulation.
• loadTextures
  • void glGenTextures(GLsizei n, GLuint * textures);
    • As with other Gen commands generats names for textures.
    • glDeleteTextures
    • glLsTexture
  • void glBindTexture(GLenum target, GLuint texture);
    • Create or use a named texture, as before
      • Called once to set things up.
      • Called once each time a texture is used.
    • Target:
      • GL_TEXTURE_2D
      • GL_TEXTURE_CUBE_MAP
    • Name: returned from glGenTextures
  • void glTexImage2D(GLenum target, GLint level, GLint internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid * data);
    • Maps data to a currently bound texture
    • target:
      • GL_TEXTURE_2D
      • GL_TEXTURE_CUBE_MAP_POSITIVE_X
      • GL_TEXTURE_CUBE_MAP_NEGATIVE_X
      • GL_TEXTURE_CUBE_MAP_POSITIVE_Y
      • GL_TEXTURE_CUBE_MAP_NEGATIVE_Y
      • GL_TEXTURE_CUBE_MAP_POSITIVE_Z
      • GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
    • level: O or higher, n>0 for mipmaps (later)
    • internal format:
      • GL_ALPHA
      • GL_LUMINANCE
      • GL_LUMINANCE_ALPHA
      • GL_RGB
      • GL_RGBA
    • width, height
    • border: must be 0
    • format: must match internal format, same values accepted
    • type:
      • GL_UNSIGNED_BYTE
      • GL_UNSIGNED_SHORT_5_6_5
      • GL_UNSIGNED_SHORT_4_4_4_4
      • and GL_UNSIGNED_SHORT_5_5_5_1
    • data: a pointer to the data.
  • void glTexParameteri( GLenum target, GLenum pname, GLint param);
    • target: as in glTexImage2D
    • pname:
      • GL_TEXTURE_MIN_FILTER
      • GL_TEXTURE_MAG_FILTER
      • GL_TEXTURE_WRAP_S
      • or GL_TEXTURE_WRAP_T
    • value: wat to set it to.
  • void glTexEnvf( GLenum target, GLenum pname, GLfloat param);
    • target: GL_TEXTURE_ENV or GL_POINT_SPRITE_OES
    • pname:
      • GL_TEXTURE_ENV_MODE
      • GL_COMBINE_RGB
      • GL_COMBINE_ALPHA
      • GL_SRC0_RGB
      • GL_SRC1_RGB
      • GL_SRC2_RGB
      • GL_SRC0_ALPHA
      • GL_SRC1_ALPHA
      • GL_SRC2_ALPHA
      • GL_OPERAND0_RGB
      • GL_OPERAND1_RGB
      • GL_OPERAND2_RGB
      • GL_OPERAND0_ALPHA
      • GL_OPERAND1_ALPHA
      • GL_OPERAND2_ALPHA
      • GL_RGB_SCALE
      • GL_ALPHA_SCALE
      • or GL_COORD_REPLACE_OES.
    • Param:
      • GL_ADD
      • GL_ADD_SIGNED
      • GL_DOT3_RGB
      • GL_DOT3_RGBA
      • GL_INTERPOLATE
      • GL_MODULATE
      • GL_DECAL
      • GL_BLEND
      • GL_REPLACE
      • GL_SUBTRACT
      • GL_COMBINE
      • GL_TEXTURE
      • GL_CONSTANT
      • GL_PRIMARY_COLOR
      • GL_PREVIOUS
      • GL_SRC_COLOR
      • GL_ONE_MINUS_SRC_COLOR
      • GL_SRC_ALPHA
      • GL_ONE_MINUS_SRC_ALPHA
      • a single boolean value for the point sprite texture coordinate replacement, or 1.0, 2.0
      • or 4.0 when specifying the GL_RGB_SCALE or GL_ALPHA_SCALE.
  • void glTexCoord2f( GLfloat s, GLfloat t)
    • s and t coordinates in a texture