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Wavelength | Your Game Editing Resource | Do-it-yourself-WireFrame!
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Do-it-yourself-WireFrame! [Print this Article]
Posted by: Patrick
Date posted: Jun 30 2003
User Rating: 5 out of 5.0
Number of views: 7217
Number of comments: 2
Description: Rendering a wireframe of maps yourself
Hello folks. I've been wanting to do a second article/tutorial, and since this is incredibly easy, I figured it'd satisfy me for now. Please note that this tutorial will only work in OpenGL mode.

This tutorial will show you how to render a wireframe of Half-Life levels in-game yourself, using the TriangleAPI, and NOT loading the .BSP yourself.

Start by opening up the Client.dll workspace. Go in Tri.cpp, and make sure you have these #includes:

#include "hud.h"
#include "cl_util.h"
#include "const.h"
#include "com_model.h"
#include "studio.h"
#include "entity_state.h"
#include "cl_entity.h"
#include "dlight.h"
#include "triangleapi.h"
#include "r_studioint.h"
#include "StudioModelRenderer.h"
#include "GameStudioModelRenderer.h"

Now, right below those, you want to tell the compiler you're using a global called IEngineStudio. So, paste this:

extern engine_studio_api_t IEngineStudio;

Half-Life stores the map/bsp data in several data structures located in com_model.h (..\common\). The one we are particularly interested in is model_s.
engine_studio_api_t has a method called GetModelByIndex, which is what we need to get our model.

Now, somewhere above HUD_DrawNormalTriangles, add this function:

void RenderWireFrame (void)
    // all valid model_s' stored in the engine start at 1 by this method, not 0,
    // and the world model is always the first model.  Thus, it's at index 1.
    model_s *pModel = IEngineStudio.GetModelByIndex (1);

    // make sure it's a valid model_s pointer and the model type is mod_brush
    if ((pModel == NULL) || (pModel->type != mod_brush))

    // now it shouldn't crash if we do this
    // we're simply drawing every single edge in the world
    gEngfuncs.pTriAPI->Begin (TRI_LINES);
    gEngfuncs.pTriAPI->CullFace (TRI_NONE); // don't cull
    gEngfuncs.pTriAPI->RenderMode (kRenderNormal);  // normal render mode
    gEngfuncs.pTriAPI->Color4ub (255, 255, 255, 255);   // white lines

    // for all edges in the map
    for (int i = 0; i < pModel->numedges; i++)
        // get the current edge at index i
        medge_t currentEdge = pModel->edges[i];
        // the medge_t's simply store indexes into a master vertex (mvertex_t) list,
        // so get those two vertexes
        mvertex_t currentVertexes[2] =

        // now render this edge/line
        gEngfuncs.pTriAPI->Vertex3fv (currentVertexes[0].position);
        gEngfuncs.pTriAPI->Vertex3fv (currentVertexes[1].position);

    gEngfuncs.pTriAPI->End ();  // we're done rendering

All that's left is calling this function from within HUD_DrawNormalTriangles:

void DLLEXPORT HUD_DrawNormalTriangles( void )
    RenderWireFrame ();

Done. Compile and test.

This tutorial is the first of a few I plan on doing involving the world triangle data. Perhaps I'll update it to only render visible edges, which is renderer API-dependent, so it's a little more complex.

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User Comments Showing comments 1-2

Posted By: cct on Jan 23 2004 at 18:30:27
hm i thought world model is model 0

Posted By: InternetNightmare on May 26 2004 at 08:57:42
This tutorial works in DirectX mode as well :)

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