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Add ortho projection
This commit is contained in:
Miloslav Ciz
parent
63a241a0a5
commit
6a2cfb5ce6
3 changed files with 28 additions and 38 deletions
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@ -55,6 +55,7 @@ PC (SDL, offline rendering, terminal):
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- **Extremely portable** due to no dependencies, no float, no build systems, low HW requirements, endian independence etc.
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- **Many compile-time options** to tune the performance vs quality.
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- **Similar to OpenGL** in principle, but simpler, easier to use, with higher-level features.
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- **Perspective and orthographic** projections.
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- **Tools** (Python scripts) for converting 3D models and textures to C array format used by the library.
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- **Well commented** and formatted code. Automatic documentation (comments + provided Doxyfile).
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- Completely **free of legal restrictions**, public domain, do literally anything you want.
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1
TODO.txt
1
TODO.txt
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@ -1,4 +1,3 @@
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- orthographics projection - did I forget this lol?
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- Add option to compute sin with Bhaskaras approx instead of using a LUT.
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- camera's focallength attribute could really rather be stored in
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transformation.scale.z, while scale.x and scale.y could be used for
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64
small3dlib.h
64
small3dlib.h
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@ -10,7 +10,7 @@
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license: CC0 1.0 (public domain)
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found at https://creativecommons.org/publicdomain/zero/1.0/
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+ additional waiver of all IP
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version: 0.904d
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version: 0.905d
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Before including the library, define S3L_PIXEL_FUNCTION to the name of the
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function you'll be using to draw single pixels (this function will be called
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@ -166,7 +166,6 @@
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many rendering bugs and imprecisions happening due to overflows, but this will
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also consumer more RAM and may potentially be slower on computers with smaller
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native integer. */
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#define S3L_USE_WIDER_TYPES 0
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#endif
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@ -233,7 +232,6 @@ typedef
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3: Perform both geometrical and barycentric correction of triangle crossing
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the near plane. This is significantly more expensive but results in
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correct rendering. */
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#define S3L_NEAR_CROSS_STRATEGY 0
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#endif
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@ -243,8 +241,7 @@ typedef
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for the whole triangle. This can be used to create flat-shaded renders and
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will be a lot faster. With this option on you will probably want to use
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sorting instead of z-buffer. */
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#define S3L_FLAT 0
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#define S3L_FLAT 0
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#endif
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#if S3L_FLAT
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@ -262,7 +259,6 @@ typedef
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2: Approximation (computing only at every S3L_PC_APPROX_LENGTHth pixel).
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Quake-style approximation is used, which only computes the PC after
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S3L_PC_APPROX_LENGTH pixels. This is reasonably accurate and fast. */
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#define S3L_PERSPECTIVE_CORRECTION 0
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#endif
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@ -270,7 +266,6 @@ typedef
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/** For S3L_PERSPECTIVE_CORRECTION == 2, this specifies after how many pixels
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PC is recomputed. Should be a power of two to keep up the performance.
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Smaller is nicer but slower. */
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#define S3L_PC_APPROX_LENGTH 32
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#endif
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@ -300,13 +295,11 @@ typedef
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2: Use reduced-size z-buffer (of bytes). This is fast and somewhat accurate,
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but inaccuracies can occur and a considerable amount of memory is
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needed. */
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#define S3L_Z_BUFFER 0
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#endif
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#ifndef S3L_REDUCED_Z_BUFFER_GRANULARITY
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/** For S3L_Z_BUFFER == 2 this sets the reduced z-buffer granularity. */
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#define S3L_REDUCED_Z_BUFFER_GRANULARITY 5
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#endif
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@ -314,7 +307,6 @@ typedef
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/** Whether to use stencil buffer for drawing -- with this a pixel that would
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be resterized over an already rasterized pixel (within a frame) will be
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discarded. This is mostly for front-to-back sorted drawing. */
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#define S3L_STENCIL_BUFFER 0
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#endif
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@ -336,21 +328,18 @@ typedef
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because we prevent computing pixels that will be overwritten by nearer
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ones, but we need a 1b stencil buffer for this (enable S3L_STENCIL_BUFFER),
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so a bit more memory is needed. */
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#define S3L_SORT 0
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#endif
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#ifndef S3L_MAX_TRIANGES_DRAWN
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/** Maximum number of triangles that can be drawn in sorted modes. This
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affects the size of the cache used for triangle sorting. */
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#define S3L_MAX_TRIANGES_DRAWN 128
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#endif
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#ifndef S3L_NEAR
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/** Distance of the near clipping plane. Points in front or EXATLY ON this
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plane are considered outside the frustum. This must be >= 0. */
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#define S3L_NEAR (S3L_F / 4)
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#endif
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@ -361,7 +350,6 @@ typedef
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#ifndef S3L_NORMAL_COMPUTE_MAXIMUM_AVERAGE
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/** Affects the S3L_computeModelNormals function. See its description for
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details. */
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#define S3L_NORMAL_COMPUTE_MAXIMUM_AVERAGE 6
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#endif
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@ -371,7 +359,6 @@ typedef
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higher values can fix this -- in theory all higher values will have the same
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speed (it is a shift value), but it mustn't be too high to prevent
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overflow. */
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#define S3L_FAST_LERP_QUALITY 11
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#endif
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@ -524,7 +511,9 @@ void S3L_mat4Xmat4(S3L_Mat4 m1, S3L_Mat4 m2);
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typedef struct
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{
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S3L_Unit focalLength; ///< Defines the field of view (FOV).
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S3L_Unit focalLength; /**< Defines the field of view (FOV). 0 sets an
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orthographics projection (scale is controlled
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with camera's scale in its transform). */
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S3L_Transform3D transform;
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} S3L_Camera;
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@ -1669,6 +1658,9 @@ void S3L_transform3DInit(S3L_Transform3D *t)
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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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if (focalLength == 0)
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return;
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vector->x = (vector->x * focalLength) / vector->z;
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vector->y = (vector->y * focalLength) / vector->z;
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}
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@ -1719,8 +1711,10 @@ void S3L_project3DPointToScreen(
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result->w =
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(point.z <= 0) ? 0 :
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(
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camera.focalLength > 0 ?(
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(s * camera.focalLength * S3L_RESOLUTION_X) /
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(point.z * S3L_F)
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(point.z * S3L_F)) :
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((camera.transform.scale.x * S3L_RESOLUTION_X) / S3L_F)
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);
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}
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@ -1945,10 +1939,8 @@ void S3L_newFrame(void)
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S3L_stencilBufferClear();
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}
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/*
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the following serves to communicate info about if the triangle has been split
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and how the barycentrics should be remapped.
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*/
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/* the following serves to communicate info about if the triangle has been split
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and how the barycentrics should be remapped. */
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uint8_t _S3L_projectedTriangleState = 0; // 0 = normal, 1 = cut, 2 = split
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#if S3L_NEAR_CROSS_STRATEGY == 3
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@ -2585,7 +2577,15 @@ void S3L_makeCameraMatrix(S3L_Transform3D cameraTransform, S3L_Mat4 m)
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S3L_mat4Transpose(r); // transposing creates an inverse transform
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S3L_Mat4 s;
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S3L_makeScaleMatrix(
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cameraTransform.scale.x,
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cameraTransform.scale.y,
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cameraTransform.scale.z,s);
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S3L_mat4Xmat4(m,r);
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S3L_mat4Xmat4(m,s);
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}
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int8_t S3L_triangleWinding(
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@ -2603,11 +2603,9 @@ int8_t S3L_triangleWinding(
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return winding > 0 ? 1 : (winding < 0 ? -1 : 0);
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}
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/**
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Checks if given triangle (in Screen Space) is at least partially visible,
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/** Checks if given triangle (in Screen Space) is at least partially visible,
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i.e. returns false if the triangle is either completely outside the frustum
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(left, right, top, bottom, near) or is invisible due to backface culling.
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*/
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(left, right, top, bottom, near) or is invisible due to backface culling. */
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static inline int8_t S3L_triangleIsVisible(
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S3L_Vec4 p0,
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S3L_Vec4 p1,
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@ -2658,12 +2656,8 @@ _S3L_TriangleToSort S3L_sortArray[S3L_MAX_TRIANGES_DRAWN];
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uint16_t S3L_sortArrayLength;
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#endif
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void _S3L_projectVertex(
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const S3L_Model3D *model,
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S3L_Index triangleIndex,
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uint8_t vertex,
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S3L_Mat4 projectionMatrix,
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S3L_Vec4 *result)
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void _S3L_projectVertex(const S3L_Model3D *model, S3L_Index triangleIndex,
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uint8_t vertex, S3L_Mat4 projectionMatrix, S3L_Vec4 *result)
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{
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uint32_t vertexIndex = model->triangles[triangleIndex * 3 + vertex] * 3;
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@ -2696,12 +2690,10 @@ void _S3L_mapProjectedVertexToScreen(S3L_Vec4 *vertex, S3L_Unit focalLength)
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vertex->y = sY;
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}
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/**
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Projects a triangle to the screen. If enabled, a triangle can be potentially
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/** Projects a triangle to the screen. If enabled, a triangle can be potentially
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subdivided into two if it crosses the near plane, in which case two projected
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triangles are returned (the info about splitting or cutting the triangle is
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passed in global variables, see above).
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*/
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passed in global variables, see above). */
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void _S3L_projectTriangle(
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const S3L_Model3D *model,
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S3L_Index triangleIndex,
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@ -2712,7 +2704,6 @@ void _S3L_projectTriangle(
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_S3L_projectVertex(model,triangleIndex,0,matrix,&(transformed[0]));
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_S3L_projectVertex(model,triangleIndex,1,matrix,&(transformed[1]));
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_S3L_projectVertex(model,triangleIndex,2,matrix,&(transformed[2]));
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_S3L_projectedTriangleState = 0;
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#if S3L_NEAR_CROSS_STRATEGY == 2 || S3L_NEAR_CROSS_STRATEGY == 3
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@ -2999,7 +2990,6 @@ void S3L_drawScene(S3L_Scene scene)
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S3L_drawTriangle(transformed[3],transformed[4],transformed[5],
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modelIndex, triangleIndex);
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}
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}
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#endif
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}
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