improve triangle rasterization along Y axis
improved robustness against numerical errors incremental interpolation along Y simplified function, fewer jumps
This commit is contained in:
Bigfoot71
parent
2299b6b8e6
commit
7b7ed98873
183
src/external/rlsw.h
vendored
183
src/external/rlsw.h
vendored
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@ -805,7 +805,11 @@ static inline float sw_lerp(float a, float b, float t)
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return a + t * (b - a);
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}
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static inline void sw_lerp_vertex_PNTCH(sw_vertex_t* SW_RESTRICT out, const sw_vertex_t* SW_RESTRICT a, const sw_vertex_t* SW_RESTRICT b, float t)
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static inline void sw_lerp_vertex_PTCH(
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sw_vertex_t* SW_RESTRICT out,
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const sw_vertex_t* SW_RESTRICT a,
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const sw_vertex_t* SW_RESTRICT b,
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float t)
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{
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const float tInv = 1.0f - t;
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@ -832,6 +836,62 @@ static inline void sw_lerp_vertex_PNTCH(sw_vertex_t* SW_RESTRICT out, const sw_v
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out->homogeneous[3] = a->homogeneous[3] * tInv + b->homogeneous[3] * t;
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}
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static inline void sw_get_vertex_grad_PTCH(
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sw_vertex_t* SW_RESTRICT out,
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const sw_vertex_t* SW_RESTRICT a,
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const sw_vertex_t* SW_RESTRICT b,
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float scale)
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{
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// Calculate gradients for Position
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out->position[0] = (b->position[0] - a->position[0]) * scale;
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out->position[1] = (b->position[1] - a->position[1]) * scale;
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out->position[2] = (b->position[2] - a->position[2]) * scale;
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out->position[3] = (b->position[3] - a->position[3]) * scale;
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// Calculate gradients for Texture coordinates
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out->texcoord[0] = (b->texcoord[0] - a->texcoord[0]) * scale;
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out->texcoord[1] = (b->texcoord[1] - a->texcoord[1]) * scale;
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// Calculate gradients for Color
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out->color[0] = (b->color[0] - a->color[0]) * scale;
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out->color[1] = (b->color[1] - a->color[1]) * scale;
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out->color[2] = (b->color[2] - a->color[2]) * scale;
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out->color[3] = (b->color[3] - a->color[3]) * scale;
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// Calculate gradients for Homogeneous coordinates
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out->homogeneous[0] = (b->homogeneous[0] - a->homogeneous[0]) * scale;
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out->homogeneous[1] = (b->homogeneous[1] - a->homogeneous[1]) * scale;
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out->homogeneous[2] = (b->homogeneous[2] - a->homogeneous[2]) * scale;
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out->homogeneous[3] = (b->homogeneous[3] - a->homogeneous[3]) * scale;
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}
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static inline void sw_add_vertex_grad_PTCH(
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sw_vertex_t* SW_RESTRICT out,
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const sw_vertex_t* SW_RESTRICT gradients)
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{
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// Add gradients to Position
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out->position[0] += gradients->position[0];
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out->position[1] += gradients->position[1];
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out->position[2] += gradients->position[2];
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out->position[3] += gradients->position[3];
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// Add gradients to Texture coordinates
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out->texcoord[0] += gradients->texcoord[0];
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out->texcoord[1] += gradients->texcoord[1];
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// Add gradients to Color
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out->color[0] += gradients->color[0];
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out->color[1] += gradients->color[1];
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out->color[2] += gradients->color[2];
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out->color[3] += gradients->color[3];
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// Add gradients to Homogeneous coordinates
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out->homogeneous[0] += gradients->homogeneous[0];
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out->homogeneous[1] += gradients->homogeneous[1];
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out->homogeneous[2] += gradients->homogeneous[2];
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out->homogeneous[3] += gradients->homogeneous[3];
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}
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/* === Half Floating Point === */
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@ -2169,7 +2229,7 @@ static inline int sw_clip_##name(
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/* If transition between interior/exterior, calculate intersection point */ \
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if (prevInside != currInside) { \
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float t = FUNC_COMPUTE_T(prev->homogeneous, curr->homogeneous); \
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sw_lerp_vertex_PNTCH(&output[outputCount++], prev, curr, t); \
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sw_lerp_vertex_PTCH(&output[outputCount++], prev, curr, t); \
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} \
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\
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/* If current vertex inside, add it */ \
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@ -2341,7 +2401,7 @@ static inline void FUNC_NAME(const sw_texture_t* tex, const sw_vertex_t* start,
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\
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int xStart = (int)(start->screen[0] + 0.5f); \
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int xEnd = (int)(end->screen[0] + 0.5f); \
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int y = (int)(start->screen[1] + 0.5f); \
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int y = (int)start->screen[1]; \
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\
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/* Compute the inverse horizontal distance along the X axis */ \
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\
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@ -2471,115 +2531,100 @@ static inline void FUNC_NAME(const sw_vertex_t* v0, const sw_vertex_t* v1, const
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const sw_texture_t* tex) \
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{ \
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/* Swap vertices by increasing y */ \
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\
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if (v0->screen[1] > v1->screen[1]) { const sw_vertex_t* tmp = v0; v0 = v1; v1 = tmp; } \
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if (v1->screen[1] > v2->screen[1]) { const sw_vertex_t* tmp = v1; v1 = v2; v2 = tmp; } \
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if (v0->screen[1] > v1->screen[1]) { const sw_vertex_t* tmp = v0; v0 = v1; v1 = tmp; } \
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\
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/* Extracting coordinates from the sorted vertices */ \
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\
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float x0 = v0->screen[0], y0 = v0->screen[1]; \
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float x1 = v1->screen[0], y1 = v1->screen[1]; \
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float x2 = v2->screen[0], y2 = v2->screen[1]; \
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\
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/* Compute height differences */ \
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\
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float h20 = y2 - y0; \
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float h10 = y1 - y0; \
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float h21 = y2 - y1; \
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\
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if (h20 < 1e-6f) { \
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return; \
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} \
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\
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/* Precompute the inverse values without additional checks */ \
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float invH20 = (h20 > 1e-6f) ? 1.0f / h20 : 0.0f; \
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\
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float invH20 = 1.0f / h20; \
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float invH10 = (h10 > 1e-6f) ? 1.0f / h10 : 0.0f; \
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float invH21 = (h21 > 1e-6f) ? 1.0f / h21 : 0.0f; \
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\
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/* Pre-calculation of slopes (dx/dy) */ \
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\
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float dx02 = (x2 - x0) * invH20; \
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float dx01 = (x1 - x0) * invH10; \
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float dx12 = (x2 - x1) * invH21; \
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\
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/* Y bounds (vertical clipping) */ \
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\
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int yTop = (int)(y0 + 0.5f); \
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int yMiddle = (int)(y1 + 0.5f); \
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int yBottom = (int)(y2 + 0.5f); \
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\
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/* Global calculation of vertical texture gradients for the triangle */ \
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float duDy, dvDy; \
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if (ENABLE_TEXTURE) { \
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duDy = (v2->texcoord[0] - v0->texcoord[0]) * invH20; \
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dvDy = (v2->texcoord[1] - v0->texcoord[1]) * invH20; \
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} \
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/* Compute gradients for each side of the triangle */ \
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\
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sw_vertex_t vDy20, vDy10, vDy21; \
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sw_get_vertex_grad_PTCH(&vDy20, v2, v0, invH20); \
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sw_get_vertex_grad_PTCH(&vDy10, v1, v0, invH10); \
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sw_get_vertex_grad_PTCH(&vDy21, v2, v1, invH21); \
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\
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/* Initializing scanline variables */ \
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float xLeft = x0, xRight = x0; \
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sw_vertex_t start, end; \
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\
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sw_vertex_t vLeft = *v0; \
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vLeft.screen[0] = x0; \
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\
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sw_vertex_t vRight = *v0; \
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vRight.screen[0] = x0; \
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\
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/* Scanline for the upper part of the triangle */ \
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for (int y = yTop; y < yMiddle; y++) { \
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\
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/* Discard the lines that are degenerate */ \
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if (fabsf(xRight - xLeft) <= 1e-6f) { \
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goto discardTL; \
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for (int y = yTop; y < yMiddle; y++) \
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{ \
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vLeft.screen[1] = vRight.screen[1] = y; \
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\
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if (vLeft.screen[0] < vRight.screen[0]) { \
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FUNC_SCANLINE(tex, &vLeft, &vRight, vDy20.texcoord[0], vDy20.texcoord[1]); \
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} \
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else { \
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FUNC_SCANLINE(tex, &vRight, &vLeft, vDy20.texcoord[0], vDy20.texcoord[1]); \
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} \
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\
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/* Calculation of interpolation factors */ \
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float dy = (float)y - y0; \
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float t1 = dy * invH20; \
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float t2 = dy * invH10; \
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sw_add_vertex_grad_PTCH(&vLeft, &vDy20); \
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vLeft.screen[0] += dx02; \
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\
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/* Vertex interpolation */ \
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sw_lerp_vertex_PNTCH(&start, v0, v2, t1); \
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sw_lerp_vertex_PNTCH(&end, v0, v1, t2); \
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start.screen[0] = xLeft; \
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start.screen[1] = (float)y; \
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end.screen[0] = xRight; \
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end.screen[1] = (float)y; \
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\
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if (xLeft > xRight) { \
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sw_vertex_t tmp = start; \
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start = end; \
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end = tmp; \
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} \
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\
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FUNC_SCANLINE(tex, &start, &end, duDy, dvDy); \
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\
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/* Incremental update */ \
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discardTL: \
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xLeft += dx02; \
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xRight += dx01; \
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sw_add_vertex_grad_PTCH(&vRight, &vDy10); \
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vRight.screen[0] += dx01; \
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} \
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\
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/* Scanline for the lower part of the triangle */ \
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xRight = x1; /* Restart the right side from the second vertex */ \
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for (int y = yMiddle; y < yBottom; y++) { \
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\
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/* Discard the lines that are degenerate */ \
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if (fabsf(xRight - xLeft) <= 1e-6f) { \
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goto discardBL; \
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vRight = *v1, vRight.screen[0] = x1; \
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\
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for (int y = yMiddle; y < yBottom; y++) \
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{ \
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vLeft.screen[1] = vRight.screen[1] = y; \
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\
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if (vLeft.screen[0] < vRight.screen[0]) { \
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FUNC_SCANLINE(tex, &vLeft, &vRight, vDy20.texcoord[0], vDy20.texcoord[1]); \
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} \
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else { \
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FUNC_SCANLINE(tex, &vRight, &vLeft, vDy20.texcoord[0], vDy20.texcoord[1]); \
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} \
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\
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/* Calculation of interpolation factors */ \
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float dy = (float)y - y0; \
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float t1 = dy * invH20; \
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float t2 = (float)(y - y1) * invH21; \
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sw_add_vertex_grad_PTCH(&vLeft, &vDy20); \
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vLeft.screen[0] += dx02; \
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\
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/* Vertex interpolation */ \
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sw_lerp_vertex_PNTCH(&start, v0, v2, t1); \
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sw_lerp_vertex_PNTCH(&end, v1, v2, t2); \
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start.screen[0] = xLeft; \
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start.screen[1] = (float)y; \
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end.screen[0] = xRight; \
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end.screen[1] = (float)y; \
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\
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if (xLeft > xRight) { \
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sw_vertex_t tmp = start; \
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start = end; \
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end = tmp; \
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} \
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\
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FUNC_SCANLINE(tex, &start, &end, duDy, dvDy); \
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\
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/* Incremental update */ \
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discardBL: \
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xLeft += dx02; \
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xRight += dx12; \
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sw_add_vertex_grad_PTCH(&vRight, &vDy21); \
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vRight.screen[0] += dx12; \
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} \
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}
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