cMaterial::cMaterial()
{
// Set a default material (white)
ZeroMemory(&m_material, sizeof(D3DMATERIAL9));
SetDiffuseColor(255,255,255); // Line 3 truncation errors
}
bool cMaterial::SetDiffuseColor(char Red, char Green, char Blue)
{
m_material.Diffuse.r = 1.0f / 255.0f * (float)Red;
m_material.Diffuse.g = 1.0f / 255.0f * (float)Green;
m_material.Diffuse.b = 1.0f / 255.0f * (float)Blue;
return true;
}
truncation of constant value
Author
I'm not sure why this is happening but it seems that any constant value over 127 can't be passed to a char parameter without giving me a truncation error.
ex:
error:
c:\Documents and Settings\Dave\My Documents\Lyradis\include\cGraphics.cpp(639) : warning C4309: 'argument' : truncation of constant value
c:\Documents and Settings\Dave\My Documents\Lyradis\include\cGraphics.cpp(639) : warning C4309: 'argument' : truncation of constant value
c:\Documents and Settings\Dave\My Documents\Lyradis\include\cGraphics.cpp(639) : warning C4309: 'argument' : truncation of constant value
Any ideas why it's doing this?
the problem is there are too few bits in a char (1 for sign, and 7 for the number). You can use *unsigned* chars which will let you go from 0 to 255.
bool cMaterial::SetDiffuseColor(unsigned char Red, unsigned char Green, unsigned char Blue)
It might be thinking char is signed, which would mean its range is from -128 to 127. unsigned char should work as expected.
@Onemind: Negative numbers are two's complement, not sign + number.
@Onemind: Negative numbers are two's complement, not sign + number.
It is worth noting that in C++, the signedness of a char is implementation defined: char, signed char, and unsigned char are three distinct types.
It'd probably be safer and faster to use ints and perform the truncation yourself.
See, int is by convention defined as the natural size of a "word" on a given arcitecture. I know technically its just char <= short <= int <= long, but the general convention is int is 32 bits signed. Anyways, when you work in ints, everything speeds up by a bit, since the code doesn't have to go truncating everything all over the place.
See, int is by convention defined as the natural size of a "word" on a given arcitecture. I know technically its just char <= short <= int <= long, but the general convention is int is 32 bits signed. Anyways, when you work in ints, everything speeds up by a bit, since the code doesn't have to go truncating everything all over the place.
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