GLSL 标准化鼠标输入
我是这个着色器世界的新手，只是想尝试一些东西。我想做以下事情：
在鼠标周围的特定半径内，背景中的纹理应旋转 10°。鼠标坐标是绝对值，因此要使用它们，我必须对它们进行标准化，以便我可以在纹理中找到正确的空间。但不知怎的，这并不正常。旋转有效，但我得到的颜色信息有一点偏移。
我认为问题在于 normalize(mouse) 但我不知道如何正确执行此操作。这是着色器：
uniform sampler2D tex0;
uniform vec2 mouse;
void main() {
vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
if (distance(pos, mouse) < 90.0) {
vec2 p = gl_TexCoord[0].st;
vec2 m = normalize(mouse);
p.x = m.x + (cos(radians(10.0)) * (p.x - m.x) - sin(radians(10.0)) * (p.y - m.y));
p.y = m.y + (sin(radians(10.0)) * (p.x - m.x) + cos(radians(10.0)) * (p.y - m.y));
gl_FragColor = vec4(0.0, m.y, 0.0, 0.0);
gl_FragColor = texture2D( tex0, p );
}
else {
gl_FragColor.rgb = texture2D( tex0, gl_TexCoord[0].st ).rgb;
gl_FragColor.a = 1.0;
}
}
我正在使用 cinder 来执行此操作。
mShader.uniform( "mouse", Vec2f( m.x, 682 - m.y ) );
谢谢。
i'm new in this shader world and just want to try out something. I want to do the following:
In a specific radius around the mouse the texture in the background should rotate by 10°. The mouse coordinates are absolute values, so to work with them i have to normalize them, so i can adress the right space in the texture. But somehow this doesn't work right. The rotation works but i get the color information with a little offset.
I think the problem is the normalize(mouse)but i don't know how to do this right. Here is the shader:
uniform sampler2D tex0;
uniform vec2 mouse;
void main() {
vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
if (distance(pos, mouse) < 90.0) {
vec2 p = gl_TexCoord[0].st;
vec2 m = normalize(mouse);
p.x = m.x + (cos(radians(10.0)) * (p.x - m.x) - sin(radians(10.0)) * (p.y - m.y));
p.y = m.y + (sin(radians(10.0)) * (p.x - m.x) + cos(radians(10.0)) * (p.y - m.y));
gl_FragColor = vec4(0.0, m.y, 0.0, 0.0);
gl_FragColor = texture2D( tex0, p );
}
else {
gl_FragColor.rgb = texture2D( tex0, gl_TexCoord[0].st ).rgb;
gl_FragColor.a = 1.0;
}
}
I'm using cinder to do this.
mShader.uniform( "mouse", Vec2f( m.x, 682 - m.y ) );
Thank you.
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评论（1）
为了将绝对鼠标坐标转换为 [0,1] 范围（纹理样本所需），您不需要
normalize函数。你需要一个简单的比例：我用 GLSL 编写了它，但对你来说，在传递统一之前在 CPU 端完成会更容易，因为最初是 CPU 端知道屏幕分辨率。
In order transform absolute mouse coordinates into [0,1] range (required for a texture sample), you don't need
normalizefunction. You need a simple scale:I wrote it in GLSL, but for you it will be easier to do on CPU side before passing a uniform, because originally it's CPU side that is aware of the screen resolution.