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https://git.coom.tech/drummyfish/small3dlib.git
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Rework triangle drawing interface
This commit is contained in:
Miloslav Číž
parent
fcd7956158
commit
48c44943e9
2 changed files with 78 additions and 39 deletions
113
s3l.h
113
s3l.h
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@ -290,7 +290,7 @@ typedef struct
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} S3L_Vec4;
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#define S3L_writeVec4(v)\
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printf("Vec4: %d %d %d %d\n",(v.x),(v.y),(v.z),(v.w))
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printf("Vec4: %d %d %d %d\n",((v).x),((v).y),((v).z),((v).w))
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static inline void S3L_initVec4(S3L_Vec4 *v)
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{
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@ -800,12 +800,31 @@ int S3L_bresenhamStep(S3L_BresenhamState *state)
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return state->steps >= 0;
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}
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static inline void S3L_mapProjectionPlaneToScreen(S3L_Vec4 point,
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S3L_ScreenCoord *screenX, S3L_ScreenCoord *screenY)
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{
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*screenX =
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S3L_HALF_RESOLUTION_X +
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(point.x * S3L_HALF_RESOLUTION_X) / S3L_FRACTIONS_PER_UNIT;
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*screenY =
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S3L_HALF_RESOLUTION_Y -
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(point.y * S3L_HALF_RESOLUTION_X) / S3L_FRACTIONS_PER_UNIT;
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}
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void _S3L_drawFilledTriangle(
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S3L_ScreenCoord x0, S3L_ScreenCoord y0, S3L_Unit depth0,
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S3L_ScreenCoord x1, S3L_ScreenCoord y1, S3L_Unit depth1,
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S3L_ScreenCoord x2, S3L_ScreenCoord y2, S3L_Unit depth2,
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S3L_Vec4 point0,
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S3L_Vec4 point1,
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S3L_Vec4 point2,
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const S3L_Camera *camera,
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S3L_PixelInfo *p)
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{
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S3L_ScreenCoord x0, y0, x1, y1, x2, y2;
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S3L_mapProjectionPlaneToScreen(point0,&x0,&y0);
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S3L_mapProjectionPlaneToScreen(point1,&x1,&y1);
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S3L_mapProjectionPlaneToScreen(point2,&x2,&y2);
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S3L_ScreenCoord
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tPointX, tPointY, // top triangle point coords
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lPointX, lPointY, // left triangle point coords
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@ -1042,20 +1061,29 @@ void _S3L_drawFilledTriangle(
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#undef stepSide
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}
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void S3L_drawTriangle(
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S3L_ScreenCoord x0, S3L_ScreenCoord y0, S3L_Unit depth0,
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S3L_ScreenCoord x1, S3L_ScreenCoord y1, S3L_Unit depth1,
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S3L_ScreenCoord x2, S3L_ScreenCoord y2, S3L_Unit depth2,
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S3L_DrawConfig config,
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/**
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Draws a triangle according to given config. The vertices are specified in
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projection-plane space (NOT screen space!) -- they wll be mapped to screen
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space by thies function. If perspective correction is enabled, each vertex
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has to have a depth (Z position in camera space) specified in the Z
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component.
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*/
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void S3L_drawTriangle(S3L_Vec4 point0, S3L_Vec4 point1, S3L_Vec4 point2,
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const S3L_DrawConfig *config, const S3L_Camera *camera,
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S3L_Index triangleID)
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{
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if (config.backfaceCulling != S3L_BACKFACE_CULLING_NONE)
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{
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int cw = // matrix determinant
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x0 * y1 + y0 * x2 + x1 * y2 - y1 * x2 - y0 * x1 - x0 * y2 > 0;
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if ((config.backfaceCulling == S3L_BACKFACE_CULLING_CW && !cw) ||
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(config.backfaceCulling == S3L_BACKFACE_CULLING_CCW && cw))
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if (config->backfaceCulling != S3L_BACKFACE_CULLING_NONE)
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{
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int32_t winding = // determines CW or CCW
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(
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(point1.y - point0.y) * (point2.x - point1.x) -
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(point1.x - point0.x) * (point2.y - point1.y)
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);
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if ((config->backfaceCulling == S3L_BACKFACE_CULLING_CW && winding < 0) ||
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(config->backfaceCulling == S3L_BACKFACE_CULLING_CCW && winding >= 0))
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return;
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}
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@ -1063,11 +1091,23 @@ void S3L_drawTriangle(
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S3L_initPixelInfo(&p);
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p.triangleID = triangleID;
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if (config.mode == S3L_MODE_TRIANGLES) // triangle mode
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if (config->mode == S3L_MODE_TRIANGLES) // triangle mode
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{
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_S3L_drawFilledTriangle(x0,y0,depth0,x1,y1,depth1,x2,y2,depth2,&p);
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/* This function will perform the mapping to screen space itself, it needs
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the original values, hence no conversion here. */
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_S3L_drawFilledTriangle(point0,point1,point2,camera,&p);
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return;
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}
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else if (config.mode == S3L_MODE_LINES) // line mode
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// map to screen space
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S3L_ScreenCoord x0, y0, x1, y1, x2, y2;
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S3L_mapProjectionPlaneToScreen(point0,&x0,&y0);
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S3L_mapProjectionPlaneToScreen(point1,&x1,&y1);
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S3L_mapProjectionPlaneToScreen(point2,&x2,&y2);
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if (config->mode == S3L_MODE_LINES) // line mode
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{
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S3L_BresenhamState line;
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S3L_Unit lineLen;
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@ -1165,15 +1205,10 @@ void S3L_makeCameraMatrix(S3L_Transform3D cameraTransform, S3L_Mat4 *m)
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m);
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}
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static inline void S3L_mapCameraToScreen(S3L_Vec4 point, S3L_Camera *camera,
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S3L_ScreenCoord *screenX, S3L_ScreenCoord *screenY)
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static inline void S3L_zDivide(S3L_Vec4 *vector)
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{
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*screenX =
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S3L_HALF_RESOLUTION_X + (point.x * S3L_HALF_RESOLUTION_X) / point.z;
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*screenY =
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S3L_HALF_RESOLUTION_Y - (point.y * S3L_HALF_RESOLUTION_X) / point.z;
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// ^ S3L_FRACTIONS_PER_UNIT cancel out
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vector->x = (vector->x * S3L_FRACTIONS_PER_UNIT) / S3L_nonZero(vector->z);
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vector->y = (vector->y * S3L_FRACTIONS_PER_UNIT) / S3L_nonZero(vector->z);
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}
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void S3L_drawModelIndexed(
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@ -1181,14 +1216,13 @@ void S3L_drawModelIndexed(
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const S3L_Index triangleVertexIndices[],
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uint16_t triangleCount,
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S3L_Transform3D modelTransform,
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S3L_Camera camera,
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S3L_DrawConfig config)
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const S3L_Camera *camera,
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const S3L_DrawConfig *config)
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{
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S3L_Index triangleIndex = 0;
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S3L_Index coordIndex = 0;
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S3L_ScreenCoord sX0, sY0, sX1, sY1, sX2, sY2, d0, d1, d2;
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S3L_Vec4 pointModel;
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S3L_Vec4 pointModel, transformed0, transformed1, transformed2;
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S3L_Unit indexIndex;
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pointModel.w = S3L_FRACTIONS_PER_UNIT; // has to be "1.0" for translation
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@ -1196,12 +1230,12 @@ void S3L_drawModelIndexed(
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S3L_Mat4 mat1, mat2;
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S3L_makeWorldMatrix(modelTransform,&mat1);
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S3L_makeCameraMatrix(camera.transform,&mat2);
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S3L_makeCameraMatrix(camera->transform,&mat2);
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S3L_mat4Xmat4(&mat1,&mat2);
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while (triangleIndex < triangleCount)
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{
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#define mapCoords(n)\
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#define project(n)\
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indexIndex = triangleVertexIndices[coordIndex] * 3;\
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pointModel.x = coords[indexIndex];\
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++indexIndex; /* TODO: put into square brackets? */\
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@ -1210,14 +1244,17 @@ void S3L_drawModelIndexed(
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pointModel.z = coords[indexIndex];\
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++coordIndex;\
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S3L_vec4Xmat4(&pointModel,&mat1);\
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d##n = pointModel.z;\
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S3L_mapCameraToScreen(pointModel,&camera,&sX##n,&sY##n);
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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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S3L_zDivide(&transformed##n);
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mapCoords(0)
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mapCoords(1)
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mapCoords(2)
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project(0)
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project(1)
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project(2)
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S3L_drawTriangle(sX0,sY0,d0,sX1,sY1,d1,sX2,sY2,d2,config,triangleIndex);
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S3L_drawTriangle(transformed0,transformed1,transformed2,config,camera,
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triangleIndex);
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++triangleIndex;
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}
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@ -117,10 +117,12 @@ void draw()
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{
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clearScreen();
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//frame = 853;
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modelTransform.rotation.z = frame * 0.1;
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modelTransform.rotation.x = frame * 0.3;
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S3L_drawModelIndexed(ver,tri,12,modelTransform,camera,conf);
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S3L_drawModelIndexed(ver,tri,12,modelTransform,&camera,&conf);
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/*
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conf.backfaceCulling = S3L_BACKFACE_CULLING_NONE;
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