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Fix z-divide
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commit
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2 changed files with 26 additions and 2 deletions
15
s3l.h
15
s3l.h
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@ -323,7 +323,7 @@ typedef S3L_Unit S3L_Mat4[4][4]; /**< 4x4 matrix, used mostly for 3D
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transforms. The indexing is this:
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matrix[column][row]. */
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#define S3L_writeMat4(m)\
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printf("Mat4:\n %d %d %d %d\n %d %d %d %d\n %d %d %d %d\n %d %d %d %d\n"\
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printfi"Mat4:\n %d %d %d %d\n %d %d %d %d\n %d %d %d %d\n %d %d %d %d\n"\
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,(m)[0][0],(m)[1][0],(m)[2][0],(m)[3][0],\
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(m)[0][1],(m)[1][1],(m)[2][1],(m)[3][1],\
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(m)[0][2],(m)[1][2],(m)[2][2],(m)[3][2],\
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@ -1356,7 +1356,14 @@ void S3L_makeCameraMatrix(S3L_Transform3D cameraTransform, S3L_Mat4 *m)
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static inline void S3L_perspectiveDivide(S3L_Vec4 *vector,
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S3L_Unit focalLength)
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{
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S3L_Unit divisor = S3L_nonZero(vector->z);
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S3L_Unit divisor = vector->z > 0 ? vector->z : (-1 * (vector->z - 1));
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/* ^ This has two purposes:
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1. Prevent division by zero.
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2. Prevent a "rapid flip" of the vertex, e.g.: having a vertex
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[100,0,0.1] z-divides it to [1000,0], but when it shift a short
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distance to [100,0,-0.1], it z-divides to [-1000,0], rapidly flipping
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from right to the left. */
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vector->x = (vector->x * focalLength) / divisor;
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vector->y = (vector->y * focalLength) / divisor;
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@ -1398,8 +1405,12 @@ void S3L_drawModelIndexed(
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transformed##n.x = pointModel.x;\
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transformed##n.y = pointModel.y;\
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transformed##n.z = pointModel.z;\
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transformed##n.w = S3L_FRACTIONS_PER_UNIT;\
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S3L_perspectiveDivide(&transformed##n,camera->focalLength);
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/* TODO: maybe create an option that would use a cache here to not
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transform the same point twice? */
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project(0)
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project(1)
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project(2)
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13
testSDL.c
13
testSDL.c
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@ -127,6 +127,18 @@ S3L_DrawConfig conf;
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void draw()
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{
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/*
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if (frame % 128 == 0)
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{
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printf("frame: %d\n",frame);
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printf("camera:\n");
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printf(" translation: ");
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S3L_writeVec4(camera.transform.translation);
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printf(" rotation: ");
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S3L_writeVec4(camera.transform.rotation);
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}
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*/
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offScreenPixels = 0;
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clearScreen();
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@ -198,6 +210,7 @@ int main()
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S3L_initCamera(&camera);
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camera.transform.translation.z = -S3L_FRACTIONS_PER_UNIT * 2;
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// camera.transform.translation.x = S3L_FRACTIONS_PER_UNIT;
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// camera.transform.translation.y = S3L_FRACTIONS_PER_UNIT;
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