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shader.go
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shader.go
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// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package opengl
import (
"fmt"
"regexp"
"strings"
"github.com/hajimehoshi/ebiten/internal/driver"
)
// glslReservedKeywords is a set of reserved keywords that cannot be used as an indentifier on some environments.
// See https://www.khronos.org/registry/OpenGL/specs/gl/GLSLangSpec.4.60.pdf.
var glslReservedKeywords = map[string]struct{}{
"common": {}, "partition": {}, "active": {},
"asm": {},
"class": {}, "union": {}, "enum": {}, "typedef": {}, "template": {}, "this": {},
"resource": {},
"goto": {},
"inline": {}, "noinline": {}, "public": {}, "static": {}, "extern": {}, "external": {}, "interface": {},
"long": {}, "short": {}, "half": {}, "fixed": {}, "unsigned": {}, "superp": {},
"input": {}, "output": {},
"hvec2": {}, "hvec3": {}, "hvec4": {}, "fvec2": {}, "fvec3": {}, "fvec4": {},
"filter": {},
"sizeof": {}, "cast": {},
"namespace": {}, "using": {},
"sampler3DRect": {},
}
var glslIdentifier = regexp.MustCompile(`[_a-zA-Z][_a-zA-Z0-9]*`)
func checkGLSL(src string) {
for _, l := range strings.Split(src, "\n") {
if strings.Contains(l, "//") {
l = l[:strings.Index(l, "//")]
}
for _, token := range glslIdentifier.FindAllString(l, -1) {
if _, ok := glslReservedKeywords[token]; ok {
panic(fmt.Sprintf("opengl: %q is a reserved keyword", token))
}
}
}
}
func vertexShaderStr() string {
src := shaderStrVertex
checkGLSL(src)
return src
}
func fragmentShaderStr(useColorM bool, filter driver.Filter, address driver.Address) string {
replaces := map[string]string{
"{{.AddressClampToZero}}": fmt.Sprintf("%d", driver.AddressClampToZero),
"{{.AddressRepeat}}": fmt.Sprintf("%d", driver.AddressRepeat),
}
src := shaderStrFragment
for k, v := range replaces {
src = strings.Replace(src, k, v, -1)
}
var defs []string
if useColorM {
defs = append(defs, "#define USE_COLOR_MATRIX")
}
switch filter {
case driver.FilterNearest:
defs = append(defs, "#define FILTER_NEAREST")
case driver.FilterLinear:
defs = append(defs, "#define FILTER_LINEAR")
case driver.FilterScreen:
defs = append(defs, "#define FILTER_SCREEN")
default:
panic(fmt.Sprintf("opengl: invalid filter: %d", filter))
}
switch address {
case driver.AddressClampToZero:
defs = append(defs, "#define ADDRESS_CLAMP_TO_ZERO")
case driver.AddressRepeat:
defs = append(defs, "#define ADDRESS_REPEAT")
default:
panic(fmt.Sprintf("opengl: invalid address: %d", address))
}
src = strings.Replace(src, "{{.Definitions}}", strings.Join(defs, "\n"), -1)
checkGLSL(src)
return src
}
const (
shaderStrVertex = `
uniform vec2 viewport_size;
attribute vec2 vertex;
attribute vec2 tex;
attribute vec4 tex_region;
attribute vec4 color_scale;
varying vec2 varying_tex;
varying vec4 varying_tex_region;
varying vec4 varying_color_scale;
void main(void) {
varying_tex = tex;
varying_tex_region = tex_region;
varying_color_scale = color_scale;
mat4 projection_matrix = mat4(
vec4(2.0 / viewport_size.x, 0, 0, 0),
vec4(0, 2.0 / viewport_size.y, 0, 0),
vec4(0, 0, 1, 0),
vec4(-1, -1, 0, 1)
);
gl_Position = projection_matrix * vec4(vertex, 0, 1);
}
`
shaderStrFragment = `
#if defined(GL_ES)
precision mediump float;
#else
#define lowp
#define mediump
#define highp
#endif
{{.Definitions}}
uniform sampler2D texture;
#if defined(USE_COLOR_MATRIX)
uniform mat4 color_matrix_body;
uniform vec4 color_matrix_translation;
#endif
uniform highp vec2 source_size;
#if defined(FILTER_SCREEN)
uniform highp float scale;
#endif
varying highp vec2 varying_tex;
varying highp vec4 varying_tex_region;
varying highp vec4 varying_color_scale;
// adjustTexel adjusts the two texels and returns the adjusted second texel.
// When p1 - p0 is exactly equal to the texel size, jaggy can happen on macOS (#669).
// In order to avoid this jaggy, subtract a little bit from the second texel.
highp vec2 adjustTexel(highp vec2 p0, highp vec2 p1) {
highp vec2 texel_size = 1.0 / source_size;
if (fract((p1.x-p0.x)*source_size.x) == 0.0) {
p1.x -= texel_size.x / 512.0;
}
if (fract((p1.y-p0.y)*source_size.y) == 0.0) {
p1.y -= texel_size.y / 512.0;
}
return p1;
}
highp float floorMod(highp float x, highp float y) {
if (x < 0.0) {
return y - (-x - y * floor(-x/y));
}
return x - y * floor(x/y);
}
highp vec2 adjustTexelByAddress(highp vec2 p, highp vec4 tex_region) {
#if defined(ADDRESS_CLAMP_TO_ZERO)
return p;
#endif
#if defined(ADDRESS_REPEAT)
highp vec2 o = vec2(tex_region[0], tex_region[1]);
highp vec2 size = vec2(tex_region[2] - tex_region[0], tex_region[3] - tex_region[1]);
return vec2(floorMod((p.x - o.x), size.x) + o.x, floorMod((p.y - o.y), size.y) + o.y);
#endif
}
void main(void) {
highp vec2 pos = varying_tex;
#if defined(FILTER_NEAREST)
vec4 color;
pos = adjustTexelByAddress(pos, varying_tex_region);
if (varying_tex_region[0] <= pos.x &&
varying_tex_region[1] <= pos.y &&
pos.x < varying_tex_region[2] &&
pos.y < varying_tex_region[3]) {
color = texture2D(texture, pos);
} else {
color = vec4(0, 0, 0, 0);
}
#endif
#if defined(FILTER_LINEAR)
vec4 color;
highp vec2 texel_size = 1.0 / source_size;
highp vec2 p0 = pos - texel_size / 2.0;
highp vec2 p1 = pos + texel_size / 2.0;
p1 = adjustTexel(p0, p1);
p0 = adjustTexelByAddress(p0, varying_tex_region);
p1 = adjustTexelByAddress(p1, varying_tex_region);
vec4 c0 = texture2D(texture, p0);
vec4 c1 = texture2D(texture, vec2(p1.x, p0.y));
vec4 c2 = texture2D(texture, vec2(p0.x, p1.y));
vec4 c3 = texture2D(texture, p1);
if (p0.x < varying_tex_region[0]) {
c0 = vec4(0, 0, 0, 0);
c2 = vec4(0, 0, 0, 0);
}
if (p0.y < varying_tex_region[1]) {
c0 = vec4(0, 0, 0, 0);
c1 = vec4(0, 0, 0, 0);
}
if (varying_tex_region[2] <= p1.x) {
c1 = vec4(0, 0, 0, 0);
c3 = vec4(0, 0, 0, 0);
}
if (varying_tex_region[3] <= p1.y) {
c2 = vec4(0, 0, 0, 0);
c3 = vec4(0, 0, 0, 0);
}
vec2 rate = fract(p0 * source_size);
color = mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y);
#endif
#if defined(FILTER_SCREEN)
highp vec2 texel_size = 1.0 / source_size;
highp vec2 half_scaled_texel_size = texel_size / 2.0 / scale;
highp vec2 p0 = pos - half_scaled_texel_size;
highp vec2 p1 = pos + half_scaled_texel_size;
p1 = adjustTexel(p0, p1);
vec4 c0 = texture2D(texture, p0);
vec4 c1 = texture2D(texture, vec2(p1.x, p0.y));
vec4 c2 = texture2D(texture, vec2(p0.x, p1.y));
vec4 c3 = texture2D(texture, p1);
// Texels must be in the source rect, so it is not necessary to check that like linear filter.
vec2 rate_center = vec2(1.0, 1.0) - half_scaled_texel_size;
vec2 rate = clamp(((fract(p0 * source_size) - rate_center) * scale) + rate_center, 0.0, 1.0);
gl_FragColor = mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y);
// Assume that a color matrix and color vector values are not used with FILTER_SCREEN.
#else
#if defined(USE_COLOR_MATRIX)
// Un-premultiply alpha.
// When the alpha is 0, 1.0 - sign(alpha) is 1.0, which means division does nothing.
color.rgb /= color.a + (1.0 - sign(color.a));
// Apply the color matrix or scale.
color = (color_matrix_body * color) + color_matrix_translation;
color *= varying_color_scale;
// Premultiply alpha
color.rgb *= color.a;
#else
vec4 s = varying_color_scale;
color *= vec4(s.r, s.g, s.b, 1.0) * s.a;
#endif
color = min(color, color.a);
gl_FragColor = color;
#endif
}
`
)