Question

我正在尝试用trin TRIANGLE_STRIP替换GL_LINE_STRIP行我想做的是我计算了每个顶点的法线向量，并在顶点着色器中使用它们以在法线方向上偏移顶点基本上我想沿着这条线画一个矩形。我在Android上使用Opengles 2.0

这是我的着色器。

uniform mat4 m;      
uniform mat4 v;      
uniform mat4 p;      
attribute vec3 pos;     
attribute vec2 normale;     
void main()                    
{                                
     float linewidth = 4.0;                         
     mat4 mv = v * m;                         
     vec4 delta = vec4(linewidth * normale.x, linewidth * normale.y, 0.0,0.0);                         
     vec4 pos2 = mv * vec4(pos.xy, 0.0, 1.0) ;                         
   gl_Position = p * (pos2 + delta);   
}

//在这里，我为每个点添加两个顶点，并为每条线计算法线。

for (int i = 0, valuesLength = values.length; i < valuesLength; i++) {//todo do not allocate
     float value = (float) values[i] / maxValue; // make it [0:1]
     Vertex v1 = new Vertex();//todo rewrite without allocatinos
     Vertex v2 = new Vertex();//todo rewrite without allocatinos
     float x = i;
     float y = value;
     if (vertices.size() > 0) {
         // copy normale vecotrs from prev vertices
         Vertex t1 = new Vertex();
         Vertex t2 = new Vertex();
         t1.x = x;
         t1.y = y;
         t1.z = 1;
         t1.normale_x = vertices.get(vertices.size() - 2).normale_x;
         t1.normale_y = vertices.get(vertices.size() - 2).normale_y;
         t2.x = x;
         t2.y = y;
         t2.z = -1;
         t2.normale_x = vertices.get(vertices.size() - 1).normale_x;
         t2.normale_y = vertices.get(vertices.size() - 1).normale_y;
         vertices.add(t1);
         vertices.add(t2);
     }
     v1.x = x ;
     v1.y = y ;
     v1.z = 1;

     v2.x = x;
     v2.y = y;
     v2.z = -1;

     vertices.add(v1);
     vertices.add(v2);


     if (i == valuesLength - 1) {
         int j = i - 1;
         //todo last vertex
     } else {
         double nextValue = (float) values[i + 1] / column.maxValue;
         double dy = nextValue - value;
         double l = (float) Math.sqrt(1f + dy * dy);
         dy /= l;
         double dx = 1f / l;

         v1.normale_x = (float) -dy * 10;
         v1.normale_y = (float) dx;
         v2.normale_x = (float) dy * 10;
         v2.normale_y = (float) -dx;
     }
}

这是我的循环

Matrix.orthoM(PROJ, 0, 0, w, 0, h, -1.0f, 1.0f);

Matrix.setIdentityM(MODEL, 0);
Matrix.scaleM(MODEL, 0, mywpx/(float)maxXValue, myhpx , 1.0f);

Matrix.setIdentityM(VIEW, 0);
Matrix.translateM(VIEW, 0, dxpx, dypx ,0);

GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, vertices.size());

我可能缺少MVP的东西，或者忘记了多方面的东西。

如果有人能指出我在哪里缺少什么或也许有一些好的资源，我将非常感激

遇到MVP并计算直线的法线向量

0 个答案: