mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 13:22:19 +02:00
126 lines
3.4 KiB
Go
126 lines
3.4 KiB
Go
// Copyright 2014 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package graphics
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type shaderId int
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const (
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shaderVertexModelview shaderId = iota
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shaderFragmentTexture
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)
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func shader(id shaderId) string {
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return shaders[id]
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}
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var shaders = map[shaderId]string{
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shaderVertexModelview: `
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uniform mat4 projection_matrix;
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attribute vec2 vertex;
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attribute vec4 tex_coord;
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attribute vec4 geo_matrix_body;
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attribute vec2 geo_matrix_translation;
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varying vec2 varying_tex_coord;
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varying vec2 varying_tex_coord_min;
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varying vec2 varying_tex_coord_max;
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void main(void) {
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varying_tex_coord = vec2(tex_coord[0], tex_coord[1]);
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varying_tex_coord_min =
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vec2(min(tex_coord[0], tex_coord[2]), min(tex_coord[1], tex_coord[3]));
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varying_tex_coord_max =
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vec2(max(tex_coord[0], tex_coord[2]), max(tex_coord[1], tex_coord[3]));
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mat4 geo_matrix = mat4(
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vec4(geo_matrix_body[0], geo_matrix_body[2], 0, 0),
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vec4(geo_matrix_body[1], geo_matrix_body[3], 0, 0),
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vec4(0, 0, 1, 0),
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vec4(geo_matrix_translation, 0, 1)
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);
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gl_Position = projection_matrix * geo_matrix * vec4(vertex, 0, 1);
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}
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`,
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shaderFragmentTexture: `
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#if defined(GL_ES)
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precision mediump float;
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#else
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#define lowp
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#define mediump
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#define highp
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#endif
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uniform sampler2D texture;
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uniform mat4 color_matrix;
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uniform vec4 color_matrix_translation;
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uniform int filter_type;
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uniform int source_width;
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uniform int source_height;
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varying vec2 varying_tex_coord;
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varying vec2 varying_tex_coord_min;
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varying vec2 varying_tex_coord_max;
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vec2 texel_size = vec2(1.0 / float(source_width), 1.0 / float(source_height));
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vec2 roundTexel(vec2 p) {
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float unit = 256.0;
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float x = floor(p.x * float(source_width) * unit + 0.5) / float(source_width) / unit;
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float y = floor(p.y * float(source_height) * unit + 0.5) / float(source_height) / unit;
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return vec2(x, y);
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}
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vec4 getColorAt(vec2 pos) {
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if (pos.x < varying_tex_coord_min.x ||
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pos.y < varying_tex_coord_min.y ||
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varying_tex_coord_max.x <= pos.x ||
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varying_tex_coord_max.y <= pos.y) {
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return vec4(0, 0, 0, 0);
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}
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return texture2D(texture, pos);
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}
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void main(void) {
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vec4 color = vec4(0, 0, 0, 0);
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vec2 pos = roundTexel(varying_tex_coord);
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if (filter_type == 1) {
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// Nearest neighbor
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color = getColorAt(pos);
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} else if (filter_type == 2) {
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// Bi-linear
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pos -= texel_size * 0.5;
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vec4 c0 = getColorAt(pos);
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vec4 c1 = getColorAt(pos + vec2(texel_size.x, 0));
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vec4 c2 = getColorAt(pos + vec2(0, texel_size.y));
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vec4 c3 = getColorAt(pos + texel_size);
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float rateX = fract(pos.x * float(source_width));
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float rateY = fract(pos.y * float(source_height));
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color = mix(mix(c0, c1, rateX), mix(c2, c3, rateX), rateY);
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}
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// Un-premultiply alpha
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if (0.0 < color.a) {
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color.rgb /= color.a;
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}
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// Apply the color matrix
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color = (color_matrix * color) + color_matrix_translation;
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color = clamp(color, 0.0, 1.0);
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// Premultiply alpha
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color.rgb *= color.a;
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gl_FragColor = color;
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}
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`,
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}
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