trueno/src/rendering/sky.jai

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draw_sky :: (cam: *Camera, worldConfig: *World_Config = null) {
mvp := create_viewproj(cam);
vs_params : Sky_Vs_Params;
world_conf : Sky_World_Config;
wc : *World_Config = ifx worldConfig == null then *(World_Config.{}) else worldConfig;
world_config_to_shader_type(wc, *world_conf);
vs_params.mvp = mvp.floats;
sg_apply_pipeline(gPipelines.sky.pipeline);
sg_apply_bindings(*gPipelines.sky.bind);
sg_apply_uniforms(UB_sky_vs_params, *(sg_range.{ ptr = *vs_params, size = size_of(type_of(vs_params)) }));
sg_apply_uniforms(UB_sky_world_config, *(sg_range.{ptr = *world_conf, size = size_of(type_of(world_conf))}));
sg_draw(0, 36, 1);
}
get_frustum_corners :: (cam: *Camera) -> [8]Vector3 {
mat_view := create_lookat(cam);
mat_proj := create_perspective(cam);
corners : [8]Vector3;
corners[0] = unproject(Vector3.{-1, -1, -1}, mat_proj, mat_view);
corners[1] = unproject(Vector3.{1, -1, -1}, mat_proj, mat_view);
corners[2] = unproject(Vector3.{1, 1, -1}, mat_proj, mat_view);
corners[3] = unproject(Vector3.{-1, 1, -1}, mat_proj, mat_view);
corners[4] = unproject(Vector3.{-1, -1, 1}, mat_proj, mat_view);
corners[5] = unproject(Vector3.{1, -1, 1}, mat_proj, mat_view);
corners[6] = unproject(Vector3.{1, 1, 1}, mat_proj, mat_view);
corners[7] = unproject(Vector3.{-1, 1, 1}, mat_proj, mat_view);
return corners;
}
create_shadow_viewproj :: (cam: *Camera, conf: *World_Config) -> Matrix4 {
up: Vector3 = .{0, 1, 0};
targetToPos := conf.sunPosition;
A := normalize(targetToPos);
B := normalize(cross(up, A));
C := cross(A, B);
camcpy := cam.*;
camcpy.far = 50;
camcpy.near = 0.5;
frustum_corners := get_frustum_corners(*camcpy);
avg : Vector3;
for frustum_corners {
avg += it;
}
avg /= 8.0;
sunCameraPosition := -targetToPos * 50.0;
view := Matrix4.{
B.x, C.x, A.x, 0,
B.y, C.y, A.y, 0,
B.z, C.z, A.z, 0,
-dot(B, sunCameraPosition), -dot(C, sunCameraPosition), -dot(A, sunCameraPosition), 1
};
proj := matrix_ortho(-15, 15, -15, 15, 0, 100);
return view*proj;
}
// taken from raymath.h
matrix_ortho :: (left: float, right: float, bottom: float, top: float, near: float, far: float) -> Matrix4 {
rl := right - left;
tb := top - bottom;
fn := far - near;
return Matrix4.{
2.0/rl,0,0,0,
0,2.0/tb,0,0,
0,0,-2/fn,0,
-(left + right)/rl, -(top+bottom)/tb, (far+near)/fn, 1
};
}