How can i convert a GL_TRIANGLE_STRIP to GL_TRIANGLES?
Let me explain it with an image:
A triangle-strip is constructed like this:
create a triangle from v1, v2, v3
create a triangle from v2, v3, v4
...
create a triangle from v5, v6, v7
Do you see the pattern?
In code it would be something like:
With a Vertex, I mean a struct containing a postion (x,y,z)
With a Triangle, I mean a struct containing three Vertex.
Obviously this won't compile, but it should give you something to get started with.
Good luck!
A triangle-strip is constructed like this:
create a triangle from v1, v2, v3
create a triangle from v2, v3, v4
...
create a triangle from v5, v6, v7
Do you see the pattern?
In code it would be something like:
int numberOfVerticesInTriangleStrip = 7;Vertex[7] triangleStrip;int pos = 0;while(pos <= numberOfVerticesInTriangleStrip - 2){ Triangle tri; tri.v1 = triangleStrip[pos]; tri.v2 = triangleStrip[pos + 1]; tri.v3 = triangleStrip[pos + 2]; pos++;}With a Vertex, I mean a struct containing a postion (x,y,z)
With a Triangle, I mean a struct containing three Vertex.
Obviously this won't compile, but it should give you something to get started with.
Good luck!
Maybe I'm just not seeing it, but shouldn't you also reverse the winding order of every second triangle?
@Trienco: You're right, I didn't think of that! Something like this should work, right?
while(pos <= numberOfVerticesInTriangleStrip - 3){ Triangle tri1; tri1.v1 = triangleStrip[pos]; tri1.v2 = triangleStrip[pos + 1]; tri1.v3 = triangleStrip[pos + 2]; Triangle tri2; tri2.v1 = triangleStrip[pos + 2]; tri2.v2 = triangleStrip[pos + 1]; tri2.v3 = triangleStrip[pos + 3]; pos++;}
Author
thanks! i white a code like this:
void buildTriangleList(void){ gTriangleNum = gTriangleStripNum - 3 + 1; g_pTriangleIndices = new GLuint[gTriangleNum * 3]; for (int i=0; i<gTriangleNum; i++) { if ((i%2)==0) { g_pTriangleIndices[i*3+0] = g_pTriangleStripIndices;<br> g_pTriangleIndices[i*<span class="cpp-number">3</span>+<span class="cpp-number">1</span>] = g_pTriangleStripIndices;<br> g_pTriangleIndices[i*<span class="cpp-number">3</span>+<span class="cpp-number">2</span>] = g_pTriangleStripIndices;<br> }<br> <span class="cpp-keyword">else</span><br> {<br> g_pTriangleIndices[i*<span class="cpp-number">3</span>+<span class="cpp-number">0</span>] = g_pTriangleStripIndices;<br> g_pTriangleIndices[i*<span class="cpp-number">3</span>+<span class="cpp-number">1</span>] = g_pTriangleStripIndices;<br> g_pTriangleIndices[i*<span class="cpp-number">3</span>+<span class="cpp-number">2</span>] = g_pTriangleStripIndices;<br> }<br> }<br><br> <span class="cpp-keyword">return</span>;<br>}<br><br><br></pre></div><!–ENDSCRIPT–> This topic is closed to new replies.
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