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fix sw_quad_is_axis_aligned

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This commit is contained in:
Bigfoot71 2025-10-28 19:44:07 +01:00
parent bf5c00f7e0
commit 2868e6acc2
1 changed files with 27 additions and 14 deletions
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41
src/external/rlsw.h vendored
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@ -2624,25 +2624,38 @@ static inline void sw_quad_clip_and_project(void)
static inline bool sw_quad_is_axis_aligned(void)
{
int horizontal = 0;
int vertical = 0;
// Reject quads with perspective projection
// The fast path assumes affine (non-perspective) quads,
// so we require all vertices to have homogeneous w = 1.0
for (int i = 0; i < 4; i++)
{
if (RLSW.vertexBuffer[i].homogeneous[3] != 1.0f) return false;
const float *v0 = RLSW.vertexBuffer[i].position;
const float *v1 = RLSW.vertexBuffer[(i + 1)%4].position;
float dx = v1[0] - v0[0];
float dy = v1[1] - v0[1];
if ((fabsf(dx) > 1e-6f) && (fabsf(dy) < 1e-6f)) horizontal++;
else if ((fabsf(dy) > 1e-6f) && (fabsf(dx) < 1e-6f)) vertical++;
else return false; // Diagonal edge -> not axis-aligned
}
return ((horizontal == 2) && (vertical == 2));
// Epsilon tolerance in screen space (pixels)
const float epsilon = 0.5f;
// Fetch screen-space positions for the four quad vertices
const float *p0 = RLSW.vertexBuffer[0].screen;
const float *p1 = RLSW.vertexBuffer[1].screen;
const float *p2 = RLSW.vertexBuffer[2].screen;
const float *p3 = RLSW.vertexBuffer[3].screen;
// Compute edge vectors between consecutive vertices
// These define the four sides of the quad in screen space
float dx01 = p1[0] - p0[0], dy01 = p1[1] - p0[1];
float dx12 = p2[0] - p1[0], dy12 = p2[1] - p1[1];
float dx23 = p3[0] - p2[0], dy23 = p3[1] - p2[1];
float dx30 = p0[0] - p3[0], dy30 = p0[1] - p3[1];
// Each edge must be either horizontal or vertical within epsilon tolerance
// If any edge deviates significantly from either axis, the quad is not axis-aligned
if (!((fabsf(dy01) < epsilon) || (fabsf(dx01) < epsilon))) return false;
if (!((fabsf(dy12) < epsilon) || (fabsf(dx12) < epsilon))) return false;
if (!((fabsf(dy23) < epsilon) || (fabsf(dx23) < epsilon))) return false;
if (!((fabsf(dy30) < epsilon) || (fabsf(dx30) < epsilon))) return false;
return true;
}
static inline void sw_quad_sort_cw(const sw_vertex_t* *output)