(GLQuake) Software Quake MDL Lighting

[mh]

Here's another step along the path to making GLQuake look as Quake was originally intended; this time we're going to fix MDL lighting so that it's consistent with software Quake. All that's changing here is the lightting algorithm used; I haven't done anything with overbrights, interpolation or anything else.

The code assumes a completely unmodified GLQuake baseline, and all code changes come from the software Quake source. You should be able to compare this with GLQuake's original, quickly and easily identify the changes made, and port them to any other engine based on that.

Code: Select all

void GL_DrawAliasFrame (aliashdr_t *paliashdr, int posenum)
{
	float 	l;
	int		i, j;
	trivertx_t	*verts;
	int		*order;
	float	*normal;
	int		count;
	float baselight = ambientlight * (1.0f / 200.0f);
	float temp;
	float alias_forward[3], alias_right[3], alias_up[3];
	float r_plightvec[3], lightvec[3] = {-1, 0, 0};

	currententity->angles[0] = -currententity->angles[0];	// stupid quake bug
	AngleVectors (currententity->angles, alias_forward, alias_right, alias_up);
	currententity->angles[0] = -currententity->angles[0];	// stupid quake bug

	// rotate the lighting vector into the model's frame of reference
	r_plightvec[0] = DotProduct (lightvec, alias_forward);
	r_plightvec[1] = -DotProduct (lightvec, alias_right);
	r_plightvec[2] = DotProduct (lightvec, alias_up);

	lastposenum = posenum;

	verts = (trivertx_t *)((byte *)paliashdr + paliashdr->posedata);
	verts += posenum * paliashdr->poseverts;
	order = (int *)((byte *)paliashdr + paliashdr->commands);

	while (1)
	{
		// get the vertex count and primitive type
		count = *order++;
		if (!count)
			break;		// done
		if (count < 0)
		{
			count = -count;
			glBegin (GL_TRIANGLE_FAN);
		}
		else
			glBegin (GL_TRIANGLE_STRIP);

		do
		{
			// texture coordinates come from the draw list
			glTexCoord2f (((float *)order)[0], ((float *)order)[1]);
			order += 2;

			// normals and vertexes come from the frame list
			temp = baselight;
			l = DotProduct (r_avertexnormals[verts->lightnormalindex], r_plightvec);

			if (l < 0)
				temp -= shadelight * l;

			glColor3f (temp, temp, temp);

			glVertex3f (verts->v[0], verts->v[1], verts->v[2]);
			verts++;
		} while (--count);

		glEnd ();
	}
}

That's all.

The key differences are that MDLs now look a LOT more coherent, like they fit into the world better, that angle quantization is totally gone, and that shading changes as you look up and down as well as right and left.

[leileilol]

Hot damn! Time to put this stuff into Quake2. This is one of the things I wanted to do in my 'software' ref_gl I hated the choppy table-based lighting.

[Baker]

Hmmmmm ...