collision_glass.cg

来自「游戏编程精粹６第中关于粒子的实时流体仿真系统,对入门的游戏开发者很有帮助．」· CG 代码 · 共 59 行

//void main(float2 par_tri_coord : TEXCOORD0,
void main(float pindex : TEXCOORD0,
		  uniform samplerRECT attr_rect : TEXUNIT0,
		  //uniform samplerRECT tri_rect  : TEXUNIT1,
		  uniform float4x4 mat_col,
		  uniform float4x4 mat_inv_col,
		  out float3 result : COLOR)
{
	float stiff = 20000.0;
	float damp = 128.0;
	//float k = 10000.0;
	//float k = 40000.0;
	float radius = 0.004;
	const float GLASS_R = 0.05;
	const float GLASS_BOTTOM = -0.08;
	const float GLASS_TOP = 0.08;
	const float EPSILON = 0.000001f;

	float4 pp = float4(f3texRECT(attr_rect, float2(pindex, 0)), 1);
	float3 vel = mul((float3x3)mat_col, f3texRECT(attr_rect, float2(pindex, 1)));

	float3 pos = mul(mat_col, pp).xyz;

	float dist = GLASS_R - sqrt(dot(pos.xy, pos.xy));
//	float dist = GLASS_R - distance(pos.xy);//sqrt(dot(pos.xy, pos.xy))
	float diff = 2.0*radius - dist;

	float3 col_force = float3(0, 0, 0);
	if (diff > EPSILON)
	{
		float3 n = -normalize(float3(pos.x, pos.y, 0.0));
		float vel0 = dot(vel, n);
		col_force += (stiff*diff - damp*vel0)*n;
//		col_force += max(k*diff - 64.0*vel0, 0.0)*n;
	}

	diff = 2.0f*radius - (pos.z - GLASS_BOTTOM);
//	diff = 2.0f*radius - pos.z;// - GLASS_BOTTOM);

	if (diff > EPSILON)
	{
		float3 n = float3(0, 0, 1);
		float vel0 = dot(vel, n);//vec3_dot(&n, &sph->vel[i]);

		col_force += (stiff*diff - damp*vel0)*n;
	}

	
	diff = 2.0f*radius - (GLASS_TOP - pos.z);
	if (diff > EPSILON)
	{
		float3 n = float3(0, 0, -1);
		float vel0 = dot(vel, n);
		col_force += (stiff*diff - damp*vel0)*n;
	}

	result = mul((float3x3)mat_inv_col, col_force);
}