demotool/shaders/raymarcher.glsl

vec3 getNormal( vec3 pos )
{
	vec2 v = vec2( .01 , 0 );
	return normalize( vec3(
			map( pos + v.xyy ).x - map( pos - v.xyy ).x ,
			map( pos + v.yxy ).x - map( pos - v.xyx ).x ,
			map( pos + v.yyx ).x - map( pos - v.yyx ).x ) );
}

// -----------------------------------------------------------------------------

vec3 march( vec3 o , vec3 d , int steps , float factor )
{
	int i = 0;
	float dist = .01 , mat = -1;

	for ( ; i < steps ; ++ i ) {
		vec2 res = map( o + d * dist );
		if ( abs( res.x ) < u_Render.z || dist > u_Render.w ) {
			break;
		}
		dist += res.x * factor;
		mat = res.y;
	}

	return vec3( dist , dist >= u_Render.w ? -1 : mat , i );
}

// -----------------------------------------------------------------------------

void main( )
{
	setCamFromUniforms( );

	vec2 uv = ( gl_FragCoord.xy / u_Resolution ) * 2 - 1;
	vec3 camDir = normalize( lookAt - camPos );
	vec3 side = normalize( cross( camUp , camDir ) );
	vec3 up = normalize( cross( camDir , side ) );
	vec3 rayDir = normalize( camDir * nearPlane
			+ uv.x * side * u_Resolution.x / u_Resolution.y
			+ uv.y * up );

	vec3 r = march( camPos , rayDir , int( u_Render.x ) , u_Render.y );
	vec3 hitPos = camPos + rayDir * r.x;

	vec3 bc = vec3( 0 );
	if ( r.y >= 0. ) {
		const int midx = int( r.y );
		const vec3 normal = getNormal( hitPos );

#if defined( USE_BP )
		// Blinn-Phong only
		bc = BP_Shade( BPMaterials[ midx ] ,
				rayDir , normal , -u_LightDir );

#else
#if defined( USE_PBR )
		// PBR only
		T_PBRMaterial material = PBRMaterials[ midx ];
		T_PBRPrecomputed precomputed = PBR_Precompute(
				material , rayDir , normal );
		bc = PBR_Shade( material , precomputed ,
				rayDir , normal , -u_LightDir );

#else
#if defined( USE_MAP_MATERIAL )
		// Remap materials through mapMaterials
		int mtype , mtidx , glowidx;
		mapMaterial( midx , mtype , mtidx , glowidx );
		if ( mtype == 0 ) {
			bc = BP_Shade( BPMaterials[ mtidx ] ,
					rayDir , normal , -u_LightDir );
		} else {
			T_PBRMaterial material = PBRMaterials[ mtidx ];
			T_PBRPrecomputed precomputed = PBR_Precompute(
					material , rayDir , normal );
			bc = PBR_Shade( material , precomputed ,
					rayDir , normal , -u_LightDir );
		}
#if defined( USE_GLOW )
		if ( glowidx > 0 ) {
			bc += Glow[ glowidx ];
		}
#endif
#endif
#endif
#endif

#ifdef USE_GLOW
#ifndef USE_MAP_MATERIAL
		bc += Glow[ midx ];
#endif
#endif
	}

	o_Color = bc;
	o_Z = r.x;
}