[vert.glsl]
#version 120
uniform mat4 u_ZoomSettings;
uniform vec4 u_TexelSize;
uniform vec4 u_ScreenSize;
attribute vec2 in_TexCoord;
attribute vec2 in_Position;
varying vec4 v_CenterX, v_CenterY, v_IndexX, v_IndexY;
void main(void)
{
gl_Position = vec4(in_Position, 0.0, 1.0);
/* Center point in [-.5,.5], apply zoom and translation
* transformation, and go back to texture coordinates
* in [0,1]. That's the ideal point we would like to
* compute the value for. Then add or remove half the
* size of a texel: the distance from this new point to
* the final point will be our error. */
vec4 offsets = vec4(0.5, -0.5, 0.015625, -0.015625);
vec4 zoomscale = vec4(u_ZoomSettings[0][2],
u_ZoomSettings[1][2],
u_ZoomSettings[2][2],
u_ZoomSettings[3][2]);
vec4 zoomtx = vec4(u_ZoomSettings[0][0],
u_ZoomSettings[1][0],
u_ZoomSettings[2][0],
u_ZoomSettings[3][0]);
vec4 zoomty = vec4(u_ZoomSettings[0][1],
u_ZoomSettings[1][1],
u_ZoomSettings[2][1],
u_ZoomSettings[3][1]);
v_CenterX = zoomscale * in_TexCoord.x + zoomtx
+ offsets.xyxy * u_TexelSize.x;
v_CenterY = zoomscale * in_TexCoord.y - zoomty
+ offsets.xyyx * u_TexelSize.y;
/* Precompute the multiple of one texel where our ideal
* point lies. The fragment shader will call floor() on
* this value. We add or remove a slight offset to avoid
* rounding issues at the image's edges. */
v_IndexX = v_CenterX * u_ScreenSize.z - offsets.zwzw;
v_IndexY = v_CenterY * u_ScreenSize.w - offsets.zwwz;
}
[frag.glsl]
#version 120
#if defined GL_ES
precision highp float;
#endif
uniform vec4 u_TexelSize;
uniform sampler2D u_Texture;
varying vec4 v_CenterX, v_CenterY, v_IndexX, v_IndexY;
void main(void)
{
vec4 v05 = vec4(0.5, 0.5, 0.5, 0.5);
vec4 rx, ry, t0, dx, dy, dd;
/* Get a pixel coordinate from each slice into rx & ry */
rx = u_TexelSize.x + u_TexelSize.z * floor(v_IndexX);
ry = u_TexelSize.y + u_TexelSize.w * floor(v_IndexY);
/* Compute inverse distance to expected pixel in dd,
* and put zero if we fall outside the texture. */
t0 = step(abs(rx - v05), v05) * step(abs(ry - v05), v05);
dx = rx - v_CenterX;
dy = ry - v_CenterY;
#if 0
vec4 dd = t0 * (abs(dx) + abs(dy));
vec4 dd = t0 / (0.001 + sqrt((dx * dx) + (dy * dy)));
#endif
dd = t0 / (0.000001 + (dx * dx) + (dy * dy));
/* Modify Y coordinate to select proper quarter. */
ry = ry * 0.25 + vec4(0.0, 0.25, 0.5, 0.75);
#if 1
# if 0
/* XXX: disabled until we can autodetect i915 */
/* t1.x <-- dd.x > dd.y */
/* t1.y <-- dd.z > dd.w */
vec2 t1 = step(dd.xz, dd.yw);
/* ret.x <-- max(rx.x, rx.y) wrt. t1.x */
/* ret.y <-- max(rx.z, rx.w) wrt. t1.y */
/* ret.z <-- max(ry.x, ry.y) wrt. t1.x */
/* ret.w <-- max(ry.z, ry.w) wrt. t1.y */
vec4 ret = mix(vec4(rx.xz, ry.xz),
vec4(rx.yw, ry.yw), t1.xyxy);
/* dd.x <-- max(dd.x, dd.y) */
/* dd.z <-- max(dd.z, dd.w) */
dd.xy = mix(dd.xz, dd.yw, t1);
/* t2 <-- dd.x > dd.z */
float t2 = step(dd.x, dd.y);
/* ret.x <-- max(ret.x, ret.y); */
/* ret.y <-- max(ret.z, ret.w); */
ret.xy = mix(ret.xz, ret.yw, t2);
# else
/* Fallback for i915 cards -- the trick to reduce the
* number of operations is to compute both step(a,b)
* and step(b,a) and hope that their sum is 1. This is
* almost always the case, and when it isn't we can
* afford to have a few wrong pixels. However, a real
* problem is when panning the image, because half the
* screen is likely to flicker. To avoid this problem,
* we cheat a little (see m_translate comment above). */
vec4 t1 = step(dd.xzyw, dd.ywxz);
vec4 ret = vec4(rx.xz, ry.xz) * t1.zwzw
+ vec4(rx.yw, ry.yw) * t1.xyxy;
dd.xy = dd.xz * t1.zw + dd.yw * t1.xy;
vec2 t2 = step(dd.xy, dd.yx);
ret.xy = ret.xz * t2.yy + ret.yw * t2.xx;
# endif
/* Nearest neighbour */
gl_FragColor = texture2D(u_Texture, ret.xy);
#else
/* Alternate version: some kind of linear interpolation */
vec4 p0 = texture2D(u_Texture, vec2(rx.x, ry.x));
vec4 p1 = texture2D(u_Texture, vec2(rx.y, ry.y));
vec4 p2 = texture2D(u_Texture, vec2(rx.z, ry.z));
vec4 p3 = texture2D(u_Texture, vec2(rx.w, ry.w));
gl_FragColor = 1.0 / (dd.x + dd.y + dd.z + dd.w)
* (dd.x * p0 + dd.y * p1 + dd.z * p2 + dd.w * p3);
#endif
}
[vert.hlsl]
void main(float2 a_Vertex : POSITION,
float2 a_TexCoord : TEXCOORD0,
uniform float4x4 u_ZoomSettings,
uniform float4 u_TexelSize,
uniform float4 u_ScreenSize,
out float4 out_Position : POSITION0,
out float4 v_CenterX : TEXCOORD0,
out float4 v_CenterY : TEXCOORD1,
out float4 v_IndexX : TEXCOORD2,
out float4 v_IndexY : TEXCOORD3)
{
out_Position = float4(a_Vertex, 0.0, 1.0);
float4 offsets = float4(0.5, -0.5, 0.015625, -0.015625);
float4 zoomscale = float4(u_ZoomSettings[2][0],
u_ZoomSettings[2][1],
u_ZoomSettings[2][2],
u_ZoomSettings[2][3]);
float4 zoomtx = float4(u_ZoomSettings[0][0],
u_ZoomSettings[0][1],
u_ZoomSettings[0][2],
u_ZoomSettings[0][3]);
float4 zoomty = float4(u_ZoomSettings[1][0],
u_ZoomSettings[1][1],
u_ZoomSettings[1][2],
u_ZoomSettings[1][3]);
v_CenterX = zoomscale * a_TexCoord.x + zoomtx
+ offsets.xyxy * u_TexelSize.x;
v_CenterY = zoomscale * a_TexCoord.y - zoomty
+ offsets.xyyx * u_TexelSize.y;
v_IndexX = v_CenterX * u_ScreenSize.z - offsets.zwzw;
v_IndexY = v_CenterY * u_ScreenSize.w - offsets.zwwz;
}
[frag.hlsl]
void main(in float4 v_CenterX : TEXCOORD0,
in float4 v_CenterY : TEXCOORD1,
in float4 v_IndexX : TEXCOORD2,
in float4 v_IndexY : TEXCOORD3,
uniform float4 u_TexelSize,
uniform sampler2D u_Texture,
out float4 out_FragColor : COLOR)
{
float4 v05 = float4(0.5, 0.5, 0.5, 0.5);
float4 rx, ry, t0, dx, dy, dd;
rx = u_TexelSize.x + u_TexelSize.z * floor(v_IndexX);
ry = u_TexelSize.y + u_TexelSize.w * floor(v_IndexY);
t0 = step(abs(rx - v05), v05) * step(abs(ry - v05), v05);
dx = rx - v_CenterX;
dy = ry - v_CenterY;
dd = t0 / (0.000001 + (dx * dx) + (dy * dy));
ry = ry * 0.25 + float4(0.0, 0.25, 0.5, 0.75);
float2 t1 = step(dd.xz, dd.yw);
float4 ret = lerp(float4(rx.xz, ry.xz),
float4(rx.yw, ry.yw), t1.xyxy);
dd.xy = lerp(dd.xz, dd.yw, t1);
float t2 = step(dd.x, dd.y);
ret.xy = lerp(ret.xz, ret.yw, t2);
out_FragColor = tex2D(u_Texture, ret.xy);
}