bool MTexture::set(MImage &image, Type type,
bool mipmapped /* = true */,
GLenum target /* = GL_TEXTURE_2D) */)
{
unsigned int i; // used as a temporary index.
// Store the type of texture, and derive other parameters.
// (Depth is assumed to be 4 bytes per pixel RGBA.
// MImage always returns that pixel format anyway.)
m_type = type;
if ( (m_type == RGBA) || (m_type == NMAP) )
{
m_internalFormat = GL_RGBA8;
m_format = GL_RGBA;
m_componentFormat = GL_UNSIGNED_BYTE;
}
else if (m_type == HILO)
{
#if NVIDIA_SPECIFIC
m_internalFormat = GL_SIGNED_HILO_NV;
m_format = GL_HILO_NV;
m_componentFormat = GL_SHORT;
#endif
}
else assert(0);
// Get the dimension of the texture.
MStatus stat = image.getSize(m_width, m_height);
assert(stat);
m_mipmapped = mipmapped;
unsigned int maxWidthLevels = highestPowerOf2(m_width);
unsigned int maxHeightLevels = highestPowerOf2(m_height);
// Standard OpenGL doesn't accept width or height that are not power of 2.
// If that's the case we resize the picture to the closest larger valid rectangle.
bool widthIsExponent = (m_width == (unsigned int) (1 << maxWidthLevels));
bool heightIsExponent = (m_height == (unsigned int) (1 << maxHeightLevels));
if (!widthIsExponent || !heightIsExponent)
{
// Calculate the new width/height.
if (!widthIsExponent)
maxWidthLevels++;
if (!heightIsExponent)
maxHeightLevels++;
// Resize the image, without bothering to preserve the aspect ratio.
m_width = 1 << maxWidthLevels;
m_height = 1 << maxHeightLevels;
image.resize(m_width, m_height, false);
}
// Deallocate any existing levels
if (m_levels != NULL)
{
for (i=0; i < m_numLevels; i++)
{
if (m_levels[i])
{
xr_free(m_levels[i]);
m_levels[i] = NULL;
}
}
xr_free(m_levels);
}
// The number of mipmap levels cannot be greater than the exponent of width or height.
// The number of mipmap levels is 1 for a non-mipmapped texture.
// For mipmapped textures, m_numLevels = max level + 1.
m_numLevels = mipmapped ? _max(maxWidthLevels, maxHeightLevels) + 1 : 1;
// Allocate the proper amount of memory, for the base level and the mipmaps.
m_levels = xr_alloc<unsigned char*>(m_numLevels);
for (i=0; i < m_numLevels; i++)
{
m_levels[i] = xr_alloc<unsigned char>(width(i) * height(i) * 4);
}
// Copy the base level. (the actual file texture)
Memory.mem_copy(m_levels[0], image.pixels(), m_width * m_height * 4);
// Create the mipmapped levels.
// NOTE REGARDING THE width_ratio and height_ratio:
// The smallest mipmap levels of non-square textures must be handled
// carefully. Say we have a 8x2 texture. Mipmap levels will be
// 4x1, 2x1, 1x1. We cannot simply multiply the current st coordinate by
// 2 like we do for square textures to find the source st coordinates,
// or we'll end up fetching outside of the source level. Instead, we
// multiply the target s, t coordinates by the width and height ratio respectively.
for (unsigned int current_level = 1; current_level < m_numLevels; current_level++)
{
unsigned int width_ratio = width(i-1) / width(i);
unsigned int height_ratio = height(i-1) / height(i-1);
unsigned int previous_level = current_level - 1;
for (unsigned int target_t = 0; target_t < height(current_level); target_t++)
{
for (unsigned int target_s = 0; target_s < width(current_level); target_s++)
{
// The st coordinates from the source level.
unsigned int source_s = target_s * width_ratio;
unsigned int source_t = target_t * height_ratio;
unsigned int source_s2 = source_s + ((width_ratio == 2) ? 1 : 0);
unsigned int source_t2 = source_t + ((height_ratio == 2) ? 1 : 0);
unsigned char *destination = internalFetch(target_s, target_t, current_level);
unsigned char *source1 = internalFetch(source_s, source_t, previous_level);
unsigned char *source2 = internalFetch(source_s2, source_t, previous_level);
unsigned char *source3 = internalFetch(source_s, source_t2, previous_level);
unsigned char *source4 = internalFetch(source_s2, source_t2, previous_level);
// Average byte per byte.
unsigned int average1 = (*source1++ + *source2++ + *source3++ + *source4++) / 4;
*destination++ = average1;
unsigned int average2 = (*source1++ + *source2++ + *source3++ + *source4++) / 4;
*destination++ = average2;
unsigned int average3 = (*source1++ + *source2++ + *source3++ + *source4++) / 4;
*destination++ = average3;
unsigned int average4 = (*source1++ + *source2++ + *source3++ + *source4++) / 4;
*destination++ = average4;
}
}
}
if( type == NMAP )
{
// Convert each level to the NORMAL map format
//
MNormalMapConverter mapConverter;
for (unsigned int i = 0; i < m_numLevels; i++)
{
mapConverter.convertToNormalMap( m_levels[i], width(i), height(i), MNormalMapConverter::RGBA, 2.0f );
}
}
specify(target);
return true;
}
