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Diffstat (limited to '')
| -rw-r--r-- | gfx/wr/webrender/res/shared.glsl | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/gfx/wr/webrender/res/shared.glsl b/gfx/wr/webrender/res/shared.glsl new file mode 100644 index 0000000000..b784d528e6 --- /dev/null +++ b/gfx/wr/webrender/res/shared.glsl @@ -0,0 +1,192 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifdef WR_FEATURE_TEXTURE_EXTERNAL +// Please check https://www.khronos.org/registry/OpenGL/extensions/OES/OES_EGL_image_external_essl3.txt +// for this extension. +#extension GL_OES_EGL_image_external_essl3 : require +#endif + +#ifdef WR_FEATURE_ADVANCED_BLEND +#extension GL_KHR_blend_equation_advanced : require +#endif + +#ifdef WR_FEATURE_DUAL_SOURCE_BLENDING +#ifdef GL_ES +#extension GL_EXT_blend_func_extended : require +#else +#extension GL_ARB_explicit_attrib_location : require +#endif +#endif + +#include base + +#if defined(WR_FEATURE_TEXTURE_EXTERNAL) || defined(WR_FEATURE_TEXTURE_RECT) || defined(WR_FEATURE_TEXTURE_2D) +#define TEX_SAMPLE(sampler, tex_coord) texture(sampler, tex_coord.xy) +#else +#define TEX_SAMPLE(sampler, tex_coord) texture(sampler, tex_coord) +#endif + +//====================================================================================== +// Vertex shader attributes and uniforms +//====================================================================================== +#ifdef WR_VERTEX_SHADER + // A generic uniform that shaders can optionally use to configure + // an operation mode for this batch. + uniform int uMode; + + // Uniform inputs + uniform mat4 uTransform; // Orthographic projection + + // Attribute inputs + in vec2 aPosition; + + // get_fetch_uv is a macro to work around a macOS Intel driver parsing bug. + // TODO: convert back to a function once the driver issues are resolved, if ever. + // https://github.com/servo/webrender/pull/623 + // https://github.com/servo/servo/issues/13953 + // Do the division with unsigned ints because that's more efficient with D3D + #define get_fetch_uv(i, vpi) ivec2(int(vpi * (uint(i) % (WR_MAX_VERTEX_TEXTURE_WIDTH/vpi))), int(uint(i) / (WR_MAX_VERTEX_TEXTURE_WIDTH/vpi))) +#endif + +//====================================================================================== +// Fragment shader attributes and uniforms +//====================================================================================== +#ifdef WR_FRAGMENT_SHADER + // Uniform inputs + + // Fragment shader outputs + #ifdef WR_FEATURE_ADVANCED_BLEND + layout(blend_support_all_equations) out; + #endif + + #ifdef WR_FEATURE_DUAL_SOURCE_BLENDING + layout(location = 0, index = 0) out vec4 oFragColor; + layout(location = 0, index = 1) out vec4 oFragBlend; + #else + out vec4 oFragColor; + #endif + + // Write an output color in normal shaders. + void write_output(vec4 color) { + oFragColor = color; + } + + #define EPSILON 0.0001 + + // "Show Overdraw" color. Premultiplied. + #define WR_DEBUG_OVERDRAW_COLOR vec4(0.110, 0.077, 0.027, 0.125) + + float distance_to_line(vec2 p0, vec2 perp_dir, vec2 p) { + vec2 dir_to_p0 = p0 - p; + return dot(normalize(perp_dir), dir_to_p0); + } + + /// Find the appropriate half range to apply the AA approximation over. + /// This range represents a coefficient to go from one CSS pixel to half a device pixel. + float compute_aa_range(vec2 position) { + // The constant factor is chosen to compensate for the fact that length(fw) is equal + // to sqrt(2) times the device pixel ratio in the typical case. 1/sqrt(2) = 0.7071. + // + // This coefficient is chosen to ensure that any sample 0.5 pixels or more inside of + // the shape has no anti-aliasing applied to it (since pixels are sampled at their center, + // such a pixel (axis aligned) is fully inside the border). We need this so that antialiased + // curves properly connect with non-antialiased vertical or horizontal lines, among other things. + // + // Lines over a half-pixel away from the pixel center *can* intersect with the pixel square; + // indeed, unless they are horizontal or vertical, they are guaranteed to. However, choosing + // a nonzero area for such pixels causes noticeable artifacts at the junction between an anti- + // aliased corner and a straight edge. + // + // We may want to adjust this constant in specific scenarios (for example keep the principled + // value for straight edges where we want pixel-perfect equivalence with non antialiased lines + // when axis aligned, while selecting a larger and smoother aa range on curves). + #ifdef SWGL + // SWGL uses an approximation for fwidth() such that it returns equal x and y. + // Thus, 1/sqrt(2) * length((x,y)) = 1/sqrt(2) * sqrt(x*x + x*x) = x. + return fwidth(position).x; + #else + return 0.7071 * length(fwidth(position)); + #endif + } + + /// Return the blending coefficient for distance antialiasing. + /// + /// 0.0 means inside the shape, 1.0 means outside. + /// + /// This cubic polynomial approximates the area of a 1x1 pixel square under a + /// line, given the signed Euclidean distance from the center of the square to + /// that line. Calculating the *exact* area would require taking into account + /// not only this distance but also the angle of the line. However, in + /// practice, this complexity is not required, as the area is roughly the same + /// regardless of the angle. + /// + /// The coefficients of this polynomial were determined through least-squares + /// regression and are accurate to within 2.16% of the total area of the pixel + /// square 95% of the time, with a maximum error of 3.53%. + /// + /// See the comments in `compute_aa_range()` for more information on the + /// cutoff values of -0.5 and 0.5. + float distance_aa(float aa_range, float signed_distance) { + float dist = signed_distance / aa_range; + bool inside = dist <= -0.5 + EPSILON; + bool outside = dist >= 0.5 - EPSILON; + return inside || outside + ? float(inside) + : 0.5 + dist * (0.8431027 * dist * dist - 1.14453603); + } + + /// Component-wise selection. + /// + /// The idea of using this is to ensure both potential branches are executed before + /// selecting the result, to avoid observable timing differences based on the condition. + /// + /// Example usage: color = if_then_else(LessThanEqual(color, vec3(0.5)), vec3(0.0), vec3(1.0)); + /// + /// The above example sets each component to 0.0 or 1.0 independently depending on whether + /// their values are below or above 0.5. + /// + /// This is written as a macro in order to work with vectors of any dimension. + /// + /// Note: Some older android devices don't support mix with bvec. If we ever run into them + /// the only option we have is to polyfill it with a branch per component. + #define if_then_else(cond, then_branch, else_branch) mix(else_branch, then_branch, cond) +#endif + +//====================================================================================== +// Shared shader uniforms +//====================================================================================== +#ifdef WR_FEATURE_TEXTURE_2D +uniform sampler2D sColor0; +uniform sampler2D sColor1; +uniform sampler2D sColor2; +#elif defined WR_FEATURE_TEXTURE_RECT +uniform sampler2DRect sColor0; +uniform sampler2DRect sColor1; +uniform sampler2DRect sColor2; +#elif defined WR_FEATURE_TEXTURE_EXTERNAL +uniform samplerExternalOES sColor0; +uniform samplerExternalOES sColor1; +uniform samplerExternalOES sColor2; +#elif defined WR_FEATURE_TEXTURE_2D_ARRAY +uniform sampler2DArray sColor0; +uniform sampler2DArray sColor1; +uniform sampler2DArray sColor2; +#endif + +#ifdef WR_FEATURE_DITHERING +uniform sampler2D sDither; +#endif + +//====================================================================================== +// Interpolator definitions +//====================================================================================== + +//====================================================================================== +// VS only types and UBOs +//====================================================================================== + +//====================================================================================== +// VS only functions +//====================================================================================== |