renderer/src/shaders/common.glsl

/*
 * Copyright 2022 Rive
 */

// Common functions shared by multiple shaders.
#define PI float(3.141592653589793238)

#ifndef @RENDER_MODE_MSAA
#define AA_RADIUS float(.5)
#else
#define AA_RADIUS float(.0)
#endif

#ifdef GLSL
// GLSL has different semantics around precision. Normalize type conversions
// across languages with "cast_*_to_*()" methods.
INLINE half cast_float_to_half(float x) { return x; }
INLINE half cast_uint_to_half(uint x) { return float(x); }
INLINE half cast_ushort_to_half(ushort x) { return float(x); }
INLINE half cast_int_to_half(int x) { return float(x); }
INLINE half4 cast_float4_to_half4(float4 xyzw) { return xyzw; }
INLINE half2 cast_float2_to_half2(float2 xy) { return xy; }
INLINE half4 cast_uint4_to_half4(uint4 xyzw) { return vec4(xyzw); }
INLINE ushort cast_half_to_ushort(half x) { return uint(x); }
INLINE ushort cast_uint_to_ushort(uint x) { return x; }
#else
INLINE half cast_float_to_half(float x) { return (half)x; }
INLINE half cast_uint_to_half(uint x) { return (half)x; }
INLINE half cast_ushort_to_half(ushort x) { return (half)x; }
INLINE half cast_int_to_half(int x) { return (half)x; }
INLINE half4 cast_float4_to_half4(float4 xyzw) { return (half4)xyzw; }
INLINE half2 cast_float2_to_half2(float2 xy) { return (half2)xy; }
INLINE half4 cast_uint4_to_half4(uint4 xyzw) { return (half4)xyzw; }
INLINE ushort cast_half_to_ushort(half x) { return (ushort)x; }
INLINE ushort cast_uint_to_ushort(uint x) { return (ushort)x; }
#endif

INLINE half make_half(half x) { return x; }

INLINE half2 make_half2(half2 xy) { return xy; }

INLINE half2 make_half2(half x, half y)
{
    half2 ret;
    ret.x = x, ret.y = y;
    return ret;
}

INLINE half2 make_half2(half x)
{
    half2 ret;
    ret.x = x, ret.y = x;
    return ret;
}

INLINE half3 make_half3(half x, half y, half z)
{
    half3 ret;
    ret.x = x, ret.y = y, ret.z = z;
    return ret;
}

INLINE half3 make_half3(half x)
{
    half3 ret;
    ret.x = x, ret.y = x, ret.z = x;
    return ret;
}

INLINE half4 make_half4(half x, half y, half z, half w)
{
    half4 ret;
    ret.x = x, ret.y = y, ret.z = z, ret.w = w;
    return ret;
}

INLINE half4 make_half4(half3 xyz, half w)
{
    half4 ret;
    ret.xyz = xyz;
    ret.w = w;
    return ret;
}

INLINE half4 make_half4(half x)
{
    half4 ret;
    ret.x = x, ret.y = x, ret.z = x, ret.w = x;
    return ret;
}

INLINE half3x3 make_half3x3(half3 a, half3 b, half3 c)
{
    half3x3 ret;
    ret[0] = a;
    ret[1] = b;
    ret[2] = c;
    return ret;
}

INLINE half2x3 make_half2x3(half3 a, half3 b)
{
    half2x3 ret;
    ret[0] = a;
    ret[1] = b;
    return ret;
}

INLINE float2x2 make_float2x2(float4 x) { return float2x2(x.xy, x.zw); }

INLINE uint make_uint(ushort x) { return x; }

INLINE uint contour_data_idx(uint contourIDWithFlags)
{
    return (contourIDWithFlags & CONTOUR_ID_MASK) - 1u;
}

INLINE float2 unchecked_mix(float2 a, float2 b, float t)
{
    return (b - a) * t + a;
}

INLINE half id_bits_to_f16(uint idBits, uint pathIDGranularity)
{
    return idBits == 0u
               ? .0
               : unpackHalf2x16((idBits + MAX_DENORM_F16) * pathIDGranularity)
                     .r;
}

INLINE float atan2(float2 v)
{
    v = normalize(v);
    float theta = acos(clamp(v.x, -1., 1.));
    return v.y >= .0 ? theta : -theta;
}

INLINE half4 premultiply(half4 color)
{
    return make_half4(color.rgb * color.a, color.a);
}

INLINE half4 unmultiply(half4 color)
{
    if (.0 < color.a && color.a < 1.)
    {
        color.rgb *= 1. / color.a;
        // Since multiplying by the reciprocal isn't exact, and to handle
        // invalid premultiplied data, take extra steps to ensure
        // color * 1/alpha == 1 when color >= alpha.
        color.rgb = mix(color.rgb,
                        make_half3(1.),
                        greaterThan(color.rgb, make_half3(254.5 / 255.)));
    }
    return color;
}

INLINE half min_value(half4 min4)
{
    half2 min2 = min(min4.xy, min4.zw);
    half min1 = min(min2.x, min2.y);
    return min1;
}

INLINE float manhattan_width(float2 x) { return abs(x.x) + abs(x.y); }

#ifndef $UNIFORM_DEFINITIONS_AUTO_GENERATED
UNIFORM_BLOCK_BEGIN(FLUSH_UNIFORM_BUFFER_IDX, @FlushUniforms)
float gradInverseViewportY;
float tessInverseViewportY;
float renderTargetInverseViewportX;
float renderTargetInverseViewportY;
uint renderTargetWidth;
uint renderTargetHeight;
uint colorClearValue;          // Only used if clears are implemented as draws.
uint coverageClearValue;       // Only used if clears are implemented as draws.
int4 renderTargetUpdateBounds; // drawBounds, or renderTargetBounds if there is
                               // a clear. (LTRB.)
uint coverageBufferPrefix;
uint pathIDGranularity; // Spacing between adjacent path IDs (1 if IEEE
                        // compliant).
float vertexDiscardValue;
UNIFORM_BLOCK_END(uniforms)
#endif

#ifdef @VERTEX

#define RENDER_TARGET_COORD_TO_CLIP_COORD(COORD)                               \
    float4((COORD).x* uniforms.renderTargetInverseViewportX - 1.,              \
           (COORD).y * -uniforms.renderTargetInverseViewportY +                \
               sign(uniforms.renderTargetInverseViewportY),                    \
           .0,                                                                 \
           1.)

#ifndef @RENDER_MODE_MSAA
// Calculates the Manhattan distance in pixels from the given pixelPosition, to
// the point at each edge of the clipRect where coverage = 0.
//
// clipRectInverseMatrix transforms from pixel coordinates to a space where the
// clipRect is the normalized rectangle: [-1, -1, 1, 1].
INLINE float4 find_clip_rect_coverage_distances(float2x2 clipRectInverseMatrix,
                                                float2 clipRectInverseTranslate,
                                                float2 pixelPosition)
{
    float2 clipRectAAWidth =
        abs(clipRectInverseMatrix[0]) + abs(clipRectInverseMatrix[1]);
    if (clipRectAAWidth.x != .0 && clipRectAAWidth.y != .0)
    {
        float2 r = 1. / clipRectAAWidth;
        float2 clipRectCoord = MUL(clipRectInverseMatrix, pixelPosition) +
                               clipRectInverseTranslate;
        // When the center of a pixel falls exactly on an edge, coverage should
        // be .5.
        const float coverageWhenDistanceIsZero = .5;
        return float4(clipRectCoord, -clipRectCoord) * r.xyxy + r.xyxy +
               coverageWhenDistanceIsZero;
    }
    else
    {
        // The caller gave us a singular clipRectInverseMatrix. This is a
        // special case where we are expected to use tx and ty as uniform
        // coverage.
        return clipRectInverseTranslate.xyxy;
    }
}

#else // RENDER_MODE_MSAA

INLINE float normalize_z_index(uint zIndex)
{
    return 1. - float(zIndex) * (2. / 32768.);
}

#ifdef @ENABLE_CLIP_RECT
INLINE void set_clip_rect_plane_distances(float2x2 clipRectInverseMatrix,
                                          float2 clipRectInverseTranslate,
                                          float2 pixelPosition)
{
    if (clipRectInverseMatrix != float2x2(0))
    {
        float2 clipRectCoord = MUL(clipRectInverseMatrix, pixelPosition) +
                               clipRectInverseTranslate.xy;
        gl_ClipDistance[0] = clipRectCoord.x + 1.;
        gl_ClipDistance[1] = clipRectCoord.y + 1.;
        gl_ClipDistance[2] = 1. - clipRectCoord.x;
        gl_ClipDistance[3] = 1. - clipRectCoord.y;
    }
    else
    {
        // "clipRectInverseMatrix == 0" is a special case:
        //     "clipRectInverseTranslate.x == 1" => all in.
        //     "clipRectInverseTranslate.x == 0" => all out.
        gl_ClipDistance[0] = gl_ClipDistance[1] = gl_ClipDistance[2] =
            gl_ClipDistance[3] = clipRectInverseTranslate.x - .5;
    }
}
#endif // ENABLE_CLIP_RECT
#endif // RENDER_MODE_MSAA
#endif // VERTEX

#ifdef @DRAW_IMAGE
#ifndef $UNIFORM_DEFINITIONS_AUTO_GENERATED
UNIFORM_BLOCK_BEGIN(IMAGE_DRAW_UNIFORM_BUFFER_IDX, @ImageDrawUniforms)
float4 viewMatrix;
float2 translate;
float opacity;
float padding;
// clipRectInverseMatrix transforms from pixel coordinates to a space where the
// clipRect is the normalized rectangle: [-1, -1, 1, 1].
float4 clipRectInverseMatrix;
float2 clipRectInverseTranslate;
uint clipID;
uint blendMode;
uint zIndex;
UNIFORM_BLOCK_END(imageDrawUniforms)
#endif
#endif