From 48c44943e9c5a54328a17deaa0c82cc01faf4c5c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Miloslav=20=C4=8C=C3=AD=C5=BE?= Date: Thu, 9 May 2019 19:06:21 +0200 Subject: [PATCH] Rework triangle drawing interface --- s3l.h | 113 ++++++++++++++++++++++++++++++++++++------------------ testSDL.c | 4 +- 2 files changed, 78 insertions(+), 39 deletions(-) diff --git a/s3l.h b/s3l.h index 9c3d02e..2c72f55 100644 --- a/s3l.h +++ b/s3l.h @@ -290,7 +290,7 @@ typedef struct } S3L_Vec4; #define S3L_writeVec4(v)\ - printf("Vec4: %d %d %d %d\n",(v.x),(v.y),(v.z),(v.w)) + printf("Vec4: %d %d %d %d\n",((v).x),((v).y),((v).z),((v).w)) static inline void S3L_initVec4(S3L_Vec4 *v) { @@ -800,12 +800,31 @@ int S3L_bresenhamStep(S3L_BresenhamState *state) return state->steps >= 0; } +static inline void S3L_mapProjectionPlaneToScreen(S3L_Vec4 point, + S3L_ScreenCoord *screenX, S3L_ScreenCoord *screenY) +{ + *screenX = + S3L_HALF_RESOLUTION_X + + (point.x * S3L_HALF_RESOLUTION_X) / S3L_FRACTIONS_PER_UNIT; + + *screenY = + S3L_HALF_RESOLUTION_Y - + (point.y * S3L_HALF_RESOLUTION_X) / S3L_FRACTIONS_PER_UNIT; +} + void _S3L_drawFilledTriangle( - S3L_ScreenCoord x0, S3L_ScreenCoord y0, S3L_Unit depth0, - S3L_ScreenCoord x1, S3L_ScreenCoord y1, S3L_Unit depth1, - S3L_ScreenCoord x2, S3L_ScreenCoord y2, S3L_Unit depth2, + S3L_Vec4 point0, + S3L_Vec4 point1, + S3L_Vec4 point2, + const S3L_Camera *camera, S3L_PixelInfo *p) { + S3L_ScreenCoord x0, y0, x1, y1, x2, y2; + + S3L_mapProjectionPlaneToScreen(point0,&x0,&y0); + S3L_mapProjectionPlaneToScreen(point1,&x1,&y1); + S3L_mapProjectionPlaneToScreen(point2,&x2,&y2); + S3L_ScreenCoord tPointX, tPointY, // top triangle point coords lPointX, lPointY, // left triangle point coords @@ -1042,20 +1061,29 @@ void _S3L_drawFilledTriangle( #undef stepSide } -void S3L_drawTriangle( - S3L_ScreenCoord x0, S3L_ScreenCoord y0, S3L_Unit depth0, - S3L_ScreenCoord x1, S3L_ScreenCoord y1, S3L_Unit depth1, - S3L_ScreenCoord x2, S3L_ScreenCoord y2, S3L_Unit depth2, - S3L_DrawConfig config, +/** + Draws a triangle according to given config. The vertices are specified in + projection-plane space (NOT screen space!) -- they wll be mapped to screen + space by thies function. If perspective correction is enabled, each vertex + has to have a depth (Z position in camera space) specified in the Z + component. +*/ +void S3L_drawTriangle(S3L_Vec4 point0, S3L_Vec4 point1, S3L_Vec4 point2, + const S3L_DrawConfig *config, const S3L_Camera *camera, S3L_Index triangleID) { - if (config.backfaceCulling != S3L_BACKFACE_CULLING_NONE) - { - int cw = // matrix determinant - x0 * y1 + y0 * x2 + x1 * y2 - y1 * x2 - y0 * x1 - x0 * y2 > 0; - if ((config.backfaceCulling == S3L_BACKFACE_CULLING_CW && !cw) || - (config.backfaceCulling == S3L_BACKFACE_CULLING_CCW && cw)) + if (config->backfaceCulling != S3L_BACKFACE_CULLING_NONE) + { + + int32_t winding = // determines CW or CCW + ( + (point1.y - point0.y) * (point2.x - point1.x) - + (point1.x - point0.x) * (point2.y - point1.y) + ); + + if ((config->backfaceCulling == S3L_BACKFACE_CULLING_CW && winding < 0) || + (config->backfaceCulling == S3L_BACKFACE_CULLING_CCW && winding >= 0)) return; } @@ -1063,11 +1091,23 @@ void S3L_drawTriangle( S3L_initPixelInfo(&p); p.triangleID = triangleID; - if (config.mode == S3L_MODE_TRIANGLES) // triangle mode + if (config->mode == S3L_MODE_TRIANGLES) // triangle mode { - _S3L_drawFilledTriangle(x0,y0,depth0,x1,y1,depth1,x2,y2,depth2,&p); + /* This function will perform the mapping to screen space itself, it needs + the original values, hence no conversion here. */ + _S3L_drawFilledTriangle(point0,point1,point2,camera,&p); + return; } - else if (config.mode == S3L_MODE_LINES) // line mode + + // map to screen space + + S3L_ScreenCoord x0, y0, x1, y1, x2, y2; + + S3L_mapProjectionPlaneToScreen(point0,&x0,&y0); + S3L_mapProjectionPlaneToScreen(point1,&x1,&y1); + S3L_mapProjectionPlaneToScreen(point2,&x2,&y2); + + if (config->mode == S3L_MODE_LINES) // line mode { S3L_BresenhamState line; S3L_Unit lineLen; @@ -1165,15 +1205,10 @@ void S3L_makeCameraMatrix(S3L_Transform3D cameraTransform, S3L_Mat4 *m) m); } -static inline void S3L_mapCameraToScreen(S3L_Vec4 point, S3L_Camera *camera, - S3L_ScreenCoord *screenX, S3L_ScreenCoord *screenY) +static inline void S3L_zDivide(S3L_Vec4 *vector) { - *screenX = - S3L_HALF_RESOLUTION_X + (point.x * S3L_HALF_RESOLUTION_X) / point.z; - - *screenY = - S3L_HALF_RESOLUTION_Y - (point.y * S3L_HALF_RESOLUTION_X) / point.z; - // ^ S3L_FRACTIONS_PER_UNIT cancel out + vector->x = (vector->x * S3L_FRACTIONS_PER_UNIT) / S3L_nonZero(vector->z); + vector->y = (vector->y * S3L_FRACTIONS_PER_UNIT) / S3L_nonZero(vector->z); } void S3L_drawModelIndexed( @@ -1181,14 +1216,13 @@ void S3L_drawModelIndexed( const S3L_Index triangleVertexIndices[], uint16_t triangleCount, S3L_Transform3D modelTransform, - S3L_Camera camera, - S3L_DrawConfig config) + const S3L_Camera *camera, + const S3L_DrawConfig *config) { S3L_Index triangleIndex = 0; S3L_Index coordIndex = 0; - S3L_ScreenCoord sX0, sY0, sX1, sY1, sX2, sY2, d0, d1, d2; - S3L_Vec4 pointModel; + S3L_Vec4 pointModel, transformed0, transformed1, transformed2; S3L_Unit indexIndex; pointModel.w = S3L_FRACTIONS_PER_UNIT; // has to be "1.0" for translation @@ -1196,12 +1230,12 @@ void S3L_drawModelIndexed( S3L_Mat4 mat1, mat2; S3L_makeWorldMatrix(modelTransform,&mat1); - S3L_makeCameraMatrix(camera.transform,&mat2); + S3L_makeCameraMatrix(camera->transform,&mat2); S3L_mat4Xmat4(&mat1,&mat2); while (triangleIndex < triangleCount) { - #define mapCoords(n)\ + #define project(n)\ indexIndex = triangleVertexIndices[coordIndex] * 3;\ pointModel.x = coords[indexIndex];\ ++indexIndex; /* TODO: put into square brackets? */\ @@ -1210,14 +1244,17 @@ void S3L_drawModelIndexed( pointModel.z = coords[indexIndex];\ ++coordIndex;\ S3L_vec4Xmat4(&pointModel,&mat1);\ - d##n = pointModel.z;\ - S3L_mapCameraToScreen(pointModel,&camera,&sX##n,&sY##n); + transformed##n.x = pointModel.x;\ + transformed##n.y = pointModel.y;\ + transformed##n.z = pointModel.z;\ + S3L_zDivide(&transformed##n); - mapCoords(0) - mapCoords(1) - mapCoords(2) + project(0) + project(1) + project(2) - S3L_drawTriangle(sX0,sY0,d0,sX1,sY1,d1,sX2,sY2,d2,config,triangleIndex); + S3L_drawTriangle(transformed0,transformed1,transformed2,config,camera, + triangleIndex); ++triangleIndex; } diff --git a/testSDL.c b/testSDL.c index b4a0ba7..4c48ca1 100644 --- a/testSDL.c +++ b/testSDL.c @@ -117,10 +117,12 @@ void draw() { clearScreen(); +//frame = 853; + modelTransform.rotation.z = frame * 0.1; modelTransform.rotation.x = frame * 0.3; - S3L_drawModelIndexed(ver,tri,12,modelTransform,camera,conf); + S3L_drawModelIndexed(ver,tri,12,modelTransform,&camera,&conf); /* conf.backfaceCulling = S3L_BACKFACE_CULLING_NONE;