ebiten/internal/graphics/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.
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package graphics
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import (
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"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
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"strings"
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)
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type shaderId int
const (
shaderVertexModelview shaderId = iota
shaderFragmentTexture
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)
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func shader(c *opengl.Context, id shaderId) string {
str := shaders[id]
if !c.GlslHighpSupported() {
str = strings.Replace(str, "highp ", "", -1)
str = strings.Replace(str, "lowp ", "", -1)
}
return str
}
var shaders = map[shaderId]string{
shaderVertexModelview: `
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uniform highp mat4 projection_matrix;
uniform highp mat4 modelview_matrix;
attribute highp vec2 vertex;
attribute highp vec2 tex_coord;
varying highp vec2 vertex_out_tex_coord;
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void main(void) {
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vertex_out_tex_coord = tex_coord;
gl_Position = projection_matrix * modelview_matrix * vec4(vertex, 0, 1);
}
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`,
shaderFragmentTexture: `
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uniform lowp sampler2D texture;
uniform lowp mat4 color_matrix;
uniform lowp vec4 color_matrix_translation;
varying highp vec2 vertex_out_tex_coord;
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void main(void) {
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lowp vec4 color = texture2D(texture, vertex_out_tex_coord);
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if (color_matrix != mat4(1.0) || color_matrix_translation != vec4(0.0)) {
// Un-premultiply alpha
color.rgb /= color.a;
// Apply the color matrix
color = (color_matrix * color) + color_matrix_translation;
color = clamp(color, 0.0, 1.0);
// Premultiply alpha
color.rgb *= color.a;
}
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gl_FragColor = color;
}
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`,
}