[英]OpenGL : How can I pass multiple texture to a shader with one variable?
[英]How I can draw a tile from a texture tilemap in an OpenGL shader?
因此,我有一個 AtlasTexture,其中包含繪制瓷磚 map 所需的所有瓷磚。
現在我通過制服傳遞 AtlasTexture,想法是將紋理坐標更改為 select 只是我需要從圖集中獲得的部分。
問題是我只能在片段着色器上指定從零原點切割紋理,是否可以指定一個 offsetX 來告訴着色器我想從哪里開始繪制?
float vertices[] = {
// aPosition // aTextureCoordinate
0.0f, 0.0f, 0.0f, 0.0f,
100.0f, 0.0f, 1.0f, 0.0f,
0.0f, 100.0f, 0.0f, 1.0f,
100.0f, 100.0f, 1.0f, 1.0f,
};
uint32_t indices[] = {0, 1, 2, 2, 3, 1};
頂點着色器
#version 330 core
layout(location = 0) in vec2 aPosition;
layout(location = 1) in vec2 aTextureCoordinate;
out vec2 textureCoordinate;
void main() {
gl_Position = vec4( aPosition.x, aPosition.y, 1.0f, 1.0f);
textureCoordinate = vec2(
aTextureCoordinate.x / 3.0f, // This selects the first tile in the uAtlasTexture
aTextureCoordinate.y
);
}
片段着色器
#version 330 core
in vec2 textureCoordinate;
uniform sampler2D uAtlasTexture; // Has 3 tiles
out vec4 color;
void main() {
color = texture(uAtlasTexture, textureCoordinate);
}
使用Uniform變量作為偏移量。 `vec2(1.0/3.0 + aTextureCoordinate.x / 3.0f, aTextureCoordinate.y); “選擇 2 第二個瓷磚。使用制服而不是 1.0/3.0:
#version 330 core
layout(location = 0) in vec2 aPosition;
layout(location = 1) in vec2 aTextureCoordinate;
out vec2 textureCoordinate;
uniform float textureOffsetX;
void main() {
gl_Position = vec4( aPosition.x, aPosition.y, 1.0f, 1.0f);
textureCoordinate = vec2(
textureOffsetX + aTextureCoordinate.x / 3.0f,
aTextureCoordinate.y
);
}
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