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webGL 学习总结 - 持续更新 #5

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zhouzhili opened this issue Jan 21, 2019 · 0 comments

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javascript webGL

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zhouzhili commented Jan 21, 2019 •

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平移和缩放

需要掌握基本的矢量知识及相关运算方法
矢量运算中不满足乘法交换律，及 AxB 和 BxA 是不相等的，在设置变换矩阵时，应当设置为

// 点位
attribute vec4 aPosition;
// 变换矩阵
uniform mat4 uTranslateMatrix;
void main() {
  // 变换矩阵×点位矩阵
  gl_Position =uTranslateMatrix * aPosition;
}

要注意矩阵的位置，变换矩阵 × 点位矩阵

gl.readPixels

需要注意的是，前两个参数 x,y 代表的坐标系原点是 canvas 左下角，向上为 Y 轴正方向，向右为 X 轴正方形

zhouzhili added javascript webGL labels

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