Hi,
In day 33, at the end of the stream Casey does the following to compute `row` and `column` in the nested loop to draw the tiles:
Here, `rel_column` and `rel_row` are signed and can be negative while the player's tile coords are unsigned integers.
The problem I am facing is that column and row get computed as garbage values because their type is unsigned but the expression on the right hand side evaluates to a signed value. As a result the assert in `get_tile_value_unchecked` breaks the program.
This is a problem that I am having with code that I typed and Casey's code on the stream seems to working fine. So, it would be great if someone could help me understand what I might have missed.
In day 33, at the end of the stream Casey does the following to compute `row` and `column` in the nested loop to draw the tiles:
1 2 | uint32_t column = rel_column + gameState->player_p.abs_tile_x; uint32_t row = rel_row + gameState->player_p.abs_tile_y; |
Here, `rel_column` and `rel_row` are signed and can be negative while the player's tile coords are unsigned integers.
The problem I am facing is that column and row get computed as garbage values because their type is unsigned but the expression on the right hand side evaluates to a signed value. As a result the assert in `get_tile_value_unchecked` breaks the program.
This is a problem that I am having with code that I typed and Casey's code on the stream seems to working fine. So, it would be great if someone could help me understand what I might have missed.
Edited by samrat
on
I may be wrong:
we want the game world to wraps around, meaning if you go to -1 you are in fact at the maximum x position.
E.g. if we work with 8 bits, a value of -1 equals 255 in as unsigned value.
What you see as garbage value is probably the "other side" of the world (the highest int unsigned value).
we want the game world to wraps around, meaning if you go to -1 you are in fact at the maximum x position.
E.g. if we work with 8 bits, a value of -1 equals 255 in as unsigned value.
1 2 3 | int8 a = 0; int8 b = -1; uint8 c = a + b; // c = 255; |
What you see as garbage value is probably the "other side" of the world (the highest int unsigned value).