ebiten/internal/graphicsdriver/opengl/shader.go
Hajime Hoshi 4149a56524 graphics: Refactoring: Use 12 floats for each vertex
This is a preparation for #761.
2018-12-23 02:36:28 +09:00

189 lines
5.0 KiB
Go

// 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 (
"strings"
)
type shaderID int
const (
shaderVertexModelview shaderID = iota
shaderFragmentNearest
shaderFragmentLinear
shaderFragmentScreen
)
func shaderStr(id shaderID) string {
if id == shaderVertexModelview {
return shaderStrVertex
}
defs := []string{}
switch id {
case shaderFragmentNearest:
defs = append(defs, "#define FILTER_NEAREST")
case shaderFragmentLinear:
defs = append(defs, "#define FILTER_LINEAR")
case shaderFragmentScreen:
defs = append(defs, "#define FILTER_SCREEN")
default:
panic("not reached")
}
return strings.Replace(shaderStrFragment, "{{Definitions}}", strings.Join(defs, "\n"), -1)
}
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;
uniform mat4 color_matrix_body;
uniform vec4 color_matrix_translation;
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;
}
void main(void) {
highp vec2 pos = varying_tex;
highp vec2 texel_size = 1.0 / source_size;
#if defined(FILTER_NEAREST)
vec4 color = texture2D(texture, pos);
if (pos.x < varying_tex_region[0] ||
pos.y < varying_tex_region[1] ||
(varying_tex_region[2] - texel_size.x / 512.0) <= pos.x ||
(varying_tex_region[3] - texel_size.y / 512.0) <= pos.y) {
color = vec4(0, 0, 0, 0);
}
#endif
#if defined(FILTER_LINEAR)
highp vec2 p0 = pos - texel_size / 2.0;
highp vec2 p1 = pos + texel_size / 2.0;
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);
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] - texel_size.x / 512.0) <= p1.x) {
c1 = vec4(0, 0, 0, 0);
c3 = vec4(0, 0, 0, 0);
}
if ((varying_tex_region[3] - texel_size.y / 512.0) <= p1.y) {
c2 = vec4(0, 0, 0, 0);
c3 = vec4(0, 0, 0, 0);
}
vec2 rate = fract(p0 * source_size);
vec4 color = mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y);
#endif
#if defined(FILTER_SCREEN)
highp vec2 p0 = pos - texel_size / 2.0 / scale;
highp vec2 p1 = pos + texel_size / 2.0 / scale;
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 rateCenter = vec2(1.0, 1.0) - texel_size / 2.0 / scale;
vec2 rate = clamp(((fract(p0 * source_size) - rateCenter) * scale) + rateCenter, 0.0, 1.0);
vec4 color = mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y);
#endif
// Un-premultiply alpha
if (0.0 < color.a) {
color.rgb /= color.a;
}
// Apply the color matrix or scale.
color = (color_matrix_body * color) + color_matrix_translation;
color *= varying_color_scale;
color = clamp(color, 0.0, 1.0);
// Premultiply alpha
color.rgb *= color.a;
gl_FragColor = color;
}
`
)