OpenGL ES - Draw Triangle with line only?

Is there a way to draw a triangle with line only ? I think GL_开发者_运维知识库TRIANGLES option make triangle filled with color.

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Set the fill mode with glPolygonMode(face, model):

glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);

You have to set this every frame

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Is there a way to draw a triangle with line only?

Use GL_LINES, GL_LINE_STRIP , or GL_LINE_LOOP (difference see here) with the same vertices that you use for GL_TRIANGLES.

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if you are only rendering a single triangle at a time you can use GL_LINE_LOOP. it will connect the first and last, so if you have more than one triangle, it won't work.