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#ifndef __DISINFO_INC
#define __DISINFO_INC
/*
* A small font rendering library.
*
* Sample usage:
*
* fixed4 frag(v2f i) : SV_Target
* {
* float2 uv = i.uv;
* int2 cell_pos;
* float2 cell_uv;
* float2 res = int2(4, 4);
* if (!getBoxLoc(uv, 0.1, 0.9, res, cell_pos, cell_uv)) {
* return float4(0, 0, 0, 1);
* }
* float2 duv = float2(ddx(i.uv.x), ddy(i.uv.y)) / 4;
* float4 font_color = renderInBox(67, cell_uv, duv);
*
* return font_color;
* }
*/
// `_Font` should be an 8x16 (8 rows, 16 columns) grid of monospace ASCII
// glyphs.
Texture2D _Font;
float4 _Font_TexelSize;
SamplerState linear_clamp_sampler;
// Returns false if `uv` does not fall within `bounds`.
bool remapUVSmaller(float2 uv, float2 bottom_left, float2 top_right,
out float2 uvr) {
if (!(uv.x > bottom_left.x && uv.x < top_right.x &&
uv.y > bottom_left.y && uv.y < top_right.y)) {
return false;
}
uvr = uv - bottom_left;
uvr = uvr / (top_right - bottom_left);
return true;
}
// bounds: the left/right/top/bottom bounds of the inner UV region,
// respectively.
// Always returns true.
bool remapUVBigger(float2 uv, float2 bottom_left, float2 top_right,
out float2 uvr) {
uvr = uv * (top_right - bottom_left) + bottom_left;
return true;
}
bool getBoxLoc(float2 uv, float2 bottom_left, float2 top_right,
int2 res, out int2 cell_pos, out float2 cell_uv)
{
float2 box_uv;
if (!remapUVSmaller(uv, bottom_left, top_right, box_uv)) {
return false;
}
// The integer index of the cell pointed to by `uv`, on the interval
// [0, res.x - 1] * [0, res.y - 1]
cell_pos = fmod(floor(box_uv * res), res);
float2 box_sz = 1.0 / float2(res);
float2 cell_bot_left = cell_pos * box_sz;
float2 cell_top_right = (cell_pos + 1) * box_sz;
if (!remapUVSmaller(box_uv, cell_bot_left, cell_top_right, cell_uv)) {
// This should never happen Clueless
return false;
}
return true;
}
// `c` is a character encoded as ASCII.
// `duv` is float2(ddx(i.uv.x), ddy(i.uv.y)), where `i.uv` is the UV of the
// object we're rendering on.
float4 renderInBox(int c, float2 cell_uv, float2 duv)
{
int2 bitmap_res = int2(16, 8);
int letter_idx = c;
int2 letter_pos = int2(
bitmap_res.x - (letter_idx % bitmap_res.x),
letter_idx / bitmap_res.x);
letter_pos.x = bitmap_res.x - letter_pos.x;
letter_pos.y = (bitmap_res.y - 1) - letter_pos.y;
float2 letter_box_sz = 1.0 / float2(bitmap_res);
float2 letter_bot_left = letter_pos * letter_box_sz;
float2 letter_top_right = (letter_pos + 1) * letter_box_sz;
float2 letter_uv;
remapUVBigger(cell_uv, letter_bot_left, letter_top_right, letter_uv);
float4 font_color = _Font.SampleGrad(linear_clamp_sampler, letter_uv, duv.x, duv.y);
return font_color;
}
#endif // __DISINFO_INC
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