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SoftGPU: Simplify barycentric coordinate calculation to increase performance

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Flatgrass world: 57 -> 72 FPS, Vanilla world: 26 -> 34 FPS
This commit is contained in:
UnknownShadow200 2024-06-05 23:05:39 +10:00
parent dfd12d8c9f
commit c6b9d34184
1 changed files with 34 additions and 26 deletions
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60
src/Graphics_SoftGPU.c
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@ -243,35 +243,34 @@ void Gfx_DisableTextureOffset(void) {
}
void Gfx_CalcOrthoMatrix(struct Matrix* matrix, float width, float height, float zNear, float zFar) {
/* Transposed, source https://learn.microsoft.com/en-us/windows/win32/opengl/glortho */
/* Source https://learn.microsoft.com/en-us/windows/win32/direct3d9/d3dxmatrixorthooffcenterrh */
/* The simplified calculation below uses: L = 0, R = width, T = 0, B = height */
/* NOTE: This calculation is shared with Direct3D 11 backend */
*matrix = Matrix_Identity;
matrix->row1.x = 2.0f / width;
matrix->row2.y = -2.0f / height;
matrix->row3.z = -2.0f / (zFar - zNear);
matrix->row3.z = 1.0f / (zNear - zFar);
matrix->row4.x = -1.0f;
matrix->row4.y = 1.0f;
matrix->row4.z = -(zFar + zNear) / (zFar - zNear);
matrix->row4.z = zNear / (zNear - zFar);
}
static float Cotangent(float x) { return Math_CosF(x) / Math_SinF(x); }
void Gfx_CalcPerspectiveMatrix(struct Matrix* matrix, float fov, float aspect, float zFar) {
float zNear = 0.1f;
float c = Cotangent(0.5f * fov);
/* Transposed, source https://learn.microsoft.com/en-us/windows/win32/opengl/glfrustum */
/* For pos FOV based perspective matrix, left/right/top/bottom are calculated as: */
/* left = -c * aspect, right = c * aspect, bottom = -c, top = c */
/* Calculations are simplified because of left/right and top/bottom symmetry */
/* Source https://learn.microsoft.com/en-us/windows/win32/direct3d9/d3dxmatrixperspectivefovrh */
/* NOTE: This calculation is shared with Direct3D 11 backend */
float c = Cotangent(0.5f * fov);
*matrix = Matrix_Identity;
matrix->row1.x = c / aspect;
matrix->row2.y = c;
matrix->row3.z = -(zFar + zNear) / (zFar - zNear);
matrix->row3.z = zFar / (zNear - zFar);
matrix->row3.w = -1.0f;
matrix->row4.z = -(2.0f * zFar * zNear) / (zFar - zNear);
matrix->row4.z = (zNear * zFar) / (zNear - zFar);
matrix->row4.w = 0.0f;
}
@ -321,7 +320,7 @@ static CC_INLINE int FastFloor(float value) {
return valueI > value ? valueI - 1 : valueI;
}
#define edgeFunction(ax,ay, bx,by, cx,cy) ((bx - ax) * (cy - ay) - (by - ay) * (cx - ax))
#define edgeFunction(ax,ay, bx,by, cx,cy) (((bx) - (ax)) * ((cy) - (ay)) - ((by) - (ay)) * ((cx) - (ax)))
static void DrawTriangle(Vertex* V0, Vertex* V1, Vertex* V2) {
int x0 = (int)V0->x, y0 = (int)V0->y;
@ -335,7 +334,7 @@ static void DrawTriangle(Vertex* V0, Vertex* V1, Vertex* V2) {
int area = edgeFunction(x0,y0, x1,y1, x2,y2);
if (faceCulling) {
// https://gamedev.stackexchange.com/questions/203694/how-to-make-backface-culling-work-correctly-in-both-orthographic-and-perspective
if (area > 0) return;
if (area < 0) return;
}
// Reject triangles completely outside
@ -358,17 +357,27 @@ static void DrawTriangle(Vertex* V0, Vertex* V1, Vertex* V2) {
float v0 = V0->v, v1 = V1->v, v2 = V2->v;
PackedCol color = V0->c;
for (int y = minY; y <= maxY; y++) {
float yy = y + 0.5f;
for (int x = minX; x <= maxX; x++) {
float xx = x + 0.5f;
float ic0 = ((y1 - y2) * (xx - x2) + (x2 - x1) * (yy - y2)) * factor;
if (ic0 < 0 || ic0 > 1) continue;
float ic1 = ((y2 - y0) * (xx - x2) + (x0 - x2) * (yy - y2)) * factor;
if (ic1 < 0 || ic1 > 1) continue;
float ic2 = 1.0f - ic0 - ic1;
if (ic2 < 0 || ic2 > 1) continue;
// https://fgiesen.wordpress.com/2013/02/10/optimizing-the-basic-rasterizer/
int dx01 = y0 - y1, dy01 = x1 - x0;
int dx12 = y1 - y2, dy12 = x2 - x1;
int dx20 = y2 - y0, dy20 = x0 - x2;
float bc0_start = edgeFunction(x1,y1, x2,y2, minX+0.5f,minY+0.5f);
float bc1_start = edgeFunction(x2,y2, x0,y0, minX+0.5f,minY+0.5f);
float bc2_start = edgeFunction(x0,y0, x1,y1, minX+0.5f,minY+0.5f);
for (int y = minY; y <= maxY; y++, bc0_start += dy12, bc1_start += dy20, bc2_start += dy01)
{
float bc0 = bc0_start;
float bc1 = bc1_start;
float bc2 = bc2_start;
for (int x = minX; x <= maxX; x++, bc0 += dx12, bc1 += dx20, bc2 += dx01)
{
float ic0 = bc0 * factor;
float ic1 = bc1 * factor;
float ic2 = bc2 * factor;
if (ic0 < 0 || ic1 < 0 || ic2 < 0) continue;
int index = y * fb_width + x;
float w = 1 / (ic0 * w0 + ic1 * w1 + ic2 * w2);
@ -404,7 +413,6 @@ static void DrawTriangle(Vertex* V0, Vertex* V1, Vertex* V2) {
A = PackedCol_A(color);
}
if (gfx_alphaBlend) {
BitmapCol dst = colorBuffer[index];
int dstR = BitmapCol_R(dst);
@ -435,8 +443,8 @@ void DrawQuads(int startVertex, int verticesCount) {
TransformVertex(j + 2, &vertices[2]);
TransformVertex(j + 3, &vertices[3]);
DrawTriangle(&vertices[0], &vertices[1], &vertices[2]);
DrawTriangle(&vertices[2], &vertices[3], &vertices[0]);
DrawTriangle(&vertices[0], &vertices[2], &vertices[1]);
DrawTriangle(&vertices[2], &vertices[0], &vertices[3]);
}
}